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>
François
63ca17d048