build: split core/ from frontends/; prepare for multiple GUI/TUI targets

Reorganise the tree into business vs frontend as separate directories:
  src/core/{domain,imports,app}   (was system/, imports/, app/)
  src/frontends/tui/              (was tui/ + main.cpp)
  tests/tui/                      (the FTXUI-coupled helper test)
All cross-dir #include paths rewritten; same-dir includes untouched.

CMake: essim_core is the frontend-agnostic business library — links libzip,
pugixml and bsdl, NO GUI toolkit. Each frontend is a self-contained
src/frontends/<name>/ (own CMakeLists, toolkit, main.cpp) that links
essim_core, selected with -DESSIM_FRONTEND=<name> (default tui; 'none' = core +
tests only, no toolkit fetched). FTXUI moved into the tui frontend. Tests are
split: essim_tests links essim_core (no FTXUI), essim_tui_tests links essim_tui.

Verified: default tui build green (ctest 2/2); ESSIM_FRONTEND=none builds the
core + tests with FTXUI never fetched and no `essim` binary.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/core/app/export.cpp

@@ -1,13 +1,13 @@
-#include "app/export.hpp"
+#include "core/app/export.hpp"
 
-#include "imports/ods_writer.hpp"
-#include "system/connect.hpp"
-#include "system/modules.hpp"
-#include "system/parts.hpp"
-#include "system/pins.hpp"
-#include "system/signal_type.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/imports/ods_writer.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signal_type.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <cctype>
 #include <fstream>

src/core/domain/component_kind.cpp

@@ -1,4 +1,4 @@
-#include "system/component_kind.hpp"
+#include "core/domain/component_kind.hpp"
 
 #include <cctype>
 #include <string>

src/core/domain/nets.cpp

@@ -1,11 +1,11 @@
-#include "system/nets.hpp"
+#include "core/domain/nets.hpp"
 
-#include "system/connect.hpp"
-#include "system/modules.hpp"
-#include "system/parts.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <queue>
 #include <unordered_map>

src/core/domain/pin_name.cpp

@@ -1,4 +1,4 @@
-#include "system/pin_name.hpp"
+#include "core/domain/pin_name.hpp"
 
 #include <cstdio>
 #include <stdexcept>

src/core/domain/system.cpp

@@ -3,9 +3,9 @@
 
 #include "connect.hpp"
 #include "modules.hpp"
-#include "imports/import_altium.hpp"
-#include "imports/import_mentor.hpp"
-#include "imports/import_ods.hpp"
+#include "core/imports/import_altium.hpp"
+#include "core/imports/import_mentor.hpp"
+#include "core/imports/import_ods.hpp"
 
 System::System() : mods(nullptr), conns(nullptr)
 {

src/core/domain/system.hpp

@@ -1,7 +1,7 @@
 #ifndef _SYSTEM_HPP_
 #define _SYSTEM_HPP_
 
-#include "imports/import_base.hpp"
+#include "core/imports/import_base.hpp"
 
 #pragma once
 class Modules; ///< Forward declaration of the Modules class.

src/core/imports/import_altium.cpp

@@ -1,8 +1,8 @@
 #include "import_altium.hpp"
 
-#include "system/parts.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
 
 #include <cctype>
 #include <string>

src/core/imports/import_base.hpp

@@ -4,8 +4,8 @@
 #include <string>
 #include <fstream>
 
-#include "system/parts.hpp"
-#include "system/signals.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/signals.hpp"
 
 /**
  * @brief Base class for importing data from a file.

src/core/imports/import_mentor.cpp

@@ -1,6 +1,6 @@
 #include "import_mentor.hpp"
-#include "system/pins.hpp"
-#include "system/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/parts.hpp"
 
 #include <cctype>
 #include <vector>

src/core/imports/import_ods.cpp

@@ -1,8 +1,8 @@
 #include "import_ods.hpp"
 
-#include "system/parts.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
 
 #include <pugixml.hpp>
 #include <zip.h>

src/frontends/tui/CMakeLists.txt

@@ -0,0 +1,35 @@
+# TUI frontend (FTXUI). Builds the `essim` executable against essim_core.
+#
+# A frontend is self-contained here: it pulls its own GUI toolkit, compiles its
+# sources into a library that links essim_core, and produces the `essim` binary
+# from its own entry point (main.cpp). To add another frontend, create a sibling
+# src/frontends/<name>/ with the same shape and select it with
+# -DESSIM_FRONTEND=<name>.
+
+set(FTXUI_BUILD_DOCS OFF CACHE INTERNAL "")
+set(FTXUI_BUILD_EXAMPLES OFF CACHE INTERNAL "")
+set(FTXUI_BUILD_TESTS OFF CACHE INTERNAL "")
+set(FTXUI_ENABLE_INSTALL OFF CACHE INTERNAL "")
+
+FetchContent_Declare(ftxui
+  GIT_REPOSITORY https://github.com/ArthurSonzogni/FTXUI.git
+  GIT_TAG v6.1.9
+  GIT_SHALLOW TRUE
+)
+FetchContent_MakeAvailable(ftxui)
+
+# Frontend library = every .cpp here except the entry point.
+file(GLOB TUI_SOURCES "${CMAKE_CURRENT_SOURCE_DIR}/*.cpp")
+list(REMOVE_ITEM TUI_SOURCES "${CMAKE_CURRENT_SOURCE_DIR}/main.cpp")
+
+add_library(essim_tui STATIC ${TUI_SOURCES})
+target_link_libraries(essim_tui
+  PUBLIC
+    essim_core
+    ftxui::screen
+    ftxui::dom
+    ftxui::component
+)
+
+add_executable(essim "${CMAKE_CURRENT_SOURCE_DIR}/main.cpp")
+target_link_libraries(essim PRIVATE essim_tui)

src/frontends/tui/commands.cpp

@@ -1,21 +1,21 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
-#include "system/analysis.hpp"
-#include "system/connect.hpp"
-#include "system/modules.hpp"
-#include "system/nets.hpp"
-#include "system/parts.hpp"
-#include "system/persist.hpp"
-#include "system/pin_role.hpp"
-#include "system/pin_model.hpp"
-#include "system/bsdl_model.hpp"
-#include "system/bsdl_check.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
-#include "system/transform.hpp"
-#include "system/transform_vpx.hpp"
+#include "core/domain/analysis.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/nets.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/persist.hpp"
+#include "core/domain/pin_role.hpp"
+#include "core/domain/pin_model.hpp"
+#include "core/domain/bsdl_model.hpp"
+#include "core/domain/bsdl_check.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
+#include "core/domain/transform.hpp"
+#include "core/domain/transform_vpx.hpp"
 
 #include <algorithm>
 #include <cctype>

src/frontends/tui/commands_export.cpp

@@ -1,8 +1,8 @@
-#include "tui/tui.hpp"
+#include "frontends/tui/tui.hpp"
 
-#include "app/export.hpp"
-#include "system/connect.hpp"
-#include "system/system.hpp"
+#include "core/app/export.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/system.hpp"
 
 #include <string>
 #include <vector>

src/frontends/tui/completion.cpp

@@ -1,5 +1,5 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
 #include <cctype>
 #include <cstdlib>

src/frontends/tui/main.cpp

@@ -1,4 +1,4 @@
-#include "tui/tui.hpp"
+#include "frontends/tui/tui.hpp"
 
 #include <fstream>
 #include <iostream>

src/frontends/tui/screen_analyze.cpp

@@ -1,15 +1,15 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
-#include "system/analysis.hpp"
-#include "system/bsdl_check.hpp"
-#include "system/connect.hpp"
-#include "system/modules.hpp"
-#include "system/nets.hpp"
-#include "system/parts.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/analysis.hpp"
+#include "core/domain/bsdl_check.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/nets.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>

src/frontends/tui/screen_confirm.cpp

@@ -1,4 +1,4 @@
-#include "tui/tui.hpp"
+#include "frontends/tui/tui.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/event.hpp>

src/frontends/tui/screen_connect.cpp

@@ -1,11 +1,11 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
-#include "system/connect.hpp"
-#include "system/modules.hpp"
-#include "system/parts.hpp"
-#include "system/system.hpp"
-#include "system/transform.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/system.hpp"
+#include "core/domain/transform.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>

src/frontends/tui/screen_dashboard.cpp

@@ -1,15 +1,15 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
-#include "system/analysis.hpp"
-#include "system/bsdl_check.hpp"
-#include "system/connect.hpp"
-#include "system/modules.hpp"
-#include "system/nets.hpp"
-#include "system/parts.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/analysis.hpp"
+#include "core/domain/bsdl_check.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/nets.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/dom/elements.hpp>

src/frontends/tui/screen_error.cpp

@@ -1,4 +1,4 @@
-#include "tui/tui.hpp"
+#include "frontends/tui/tui.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/event.hpp>

src/frontends/tui/screen_explore.cpp

@@ -1,13 +1,13 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
-#include "system/connect.hpp"
-#include "system/modules.hpp"
-#include "system/nets.hpp"
-#include "system/parts.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/nets.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>

src/frontends/tui/screen_filedialog.cpp

@@ -1,5 +1,5 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>

src/frontends/tui/screen_help.cpp

@@ -1,5 +1,5 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>

src/frontends/tui/screen_main.cpp

@@ -1,5 +1,5 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>

src/frontends/tui/screen_palette.cpp

@@ -1,9 +1,9 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
-#include "system/modules.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>

src/frontends/tui/screen_settype.cpp

@@ -1,13 +1,13 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
-#include "system/modules.hpp"
-#include "system/parts.hpp"
-#include "system/pin_model.hpp"
-#include "system/pin_role.hpp"
-#include "system/pins.hpp"
-#include "system/system.hpp"
-#include "system/transform_vpx.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pin_model.hpp"
+#include "core/domain/pin_role.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/system.hpp"
+#include "core/domain/transform_vpx.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>

src/frontends/tui/screen_sigtype_modal.cpp

@@ -1,8 +1,8 @@
-#include "tui/tui.hpp"
+#include "frontends/tui/tui.hpp"
 
-#include "system/modules.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>

src/frontends/tui/shell.cpp

@@ -1,9 +1,9 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
-#include "system/modules.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <cctype>
 #include <chrono>

src/frontends/tui/tui.cpp

@@ -1,6 +1,6 @@
-#include "tui/tui.hpp"
+#include "frontends/tui/tui.hpp"
 
-#include "system/system.hpp"
+#include "core/domain/system.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/event.hpp>

src/frontends/tui/tui_helpers.cpp

@@ -1,4 +1,4 @@
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
 #include <ftxui/dom/elements.hpp>