restructure: code+libs under src/, runtime resources under data/

Separate the two concerns the repo root was mixing:
- src/   — bs/, modules/, libs/ (code + vendored libs)
- data/  — fpga_registry.yaml, probes.yaml, bsdl_files/, bscan_proxies/,
           scripts/ (everything the tool reads at runtime, CWD-relative)
- doc/   — kept at the root

CMake: repoint DIR_MODULES/DIR_LIBS and add_subdirectory at src/; emit
the binary at the build/ root (build/bs) via CMAKE_RUNTIME_OUTPUT_DIRECTORY
instead of the nested build/src/bs/. The jtag_core ../../libs path still
resolves since modules and libs moved together.

Runtime default paths now point under data/ (fpga.c, probes.c, script.c
bsdl_files lookup, init.c config.script). Docs (README/tutorial/CLAUDE)
updated for the new layout, src/ module paths, and ./build/bs.

Validated on the IGLOO2/FlashPro: profiles, autoinit, and svf_play all
work run from the repo root.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

data/probes.yaml

@@ -0,0 +1,31 @@
+# bs_explorer probe-config profiles
+#
+# Loaded at runtime by modules/probes/, layered on top of the built-in
+# config.script defaults. Looked up CWD-relative (run from the repo
+# root), or via $BS_PROBES.
+#
+#   defaults:  applied on every `jtag_open` (restores a known baseline
+#              so opening without a profile is deterministic).
+#   profiles:  named override sets; select with `jtag_open <idx> <name>`.
+#
+# Each key is a probe variable (see modules/config/config.script for the
+# full list); each value is what `set <KEY> <value>` would assign.
+
+defaults:
+  # Baseline for a standalone FT2232H JTAG probe: drive ADBUS4 as the
+  # "JTAG buffer enable" output (matches the built-in default).
+  PROBE_FTDI_SET_PIN_DIR_ADBUS4: 1
+  # Driver-neutral JTAG clock in kHz. Honoured by the FTDI driver (mapped
+  # to PROBE_FTDI_TCK_FREQ_KHZ at open) and our Digilent driver. Leave it
+  # out to keep each driver's own default (FTDI 1000, Digilent 4000).
+  # JTAG_TCK_FREQ_KHZ: 1000
+
+profiles:
+  # Embedded FlashPro on Microsemi eval kits (FT4232H, JTAG on channel A
+  # = probe index 0). Its ADBUS4 must be left high-Z or the chain stays
+  # silent. Usage: jtag_open 0 flashpro
+  flashpro:
+    PROBE_FTDI_SET_PIN_DIR_ADBUS4: 0
+
+  # Plain FT2232H probe: nothing to override beyond the defaults.
+  ft2232h: {}