libs 0019: remote lib edit — invalidate, don't auto-reload; editor copy counted + re-read

- kicadLibsInvalidate: a peer's edit only drops the lib's plugin entry + pcbnew's
  PreloadedFootprints (the cache the old reload never cleared — tree/preview/
  LoadFootprint/update-from-library kept serving the old body); the fat re-load
  now runs lazily or from Update-from-library (kicadLibsReload, which also
  clears the preloaded cache)
- usage bridges count the Footprint/Symbol Editor's open copy; update re-opens
  an unmodified copy, reports a modified one
- embind TU gets eeschema/symbol_editor on its include path; smoke probes
- kicad → 27051b46e2

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012Wd1r3ewftpV1DBSEArpRa

scripts/kicad/build-kicad-target.sh

@@ -602,6 +602,10 @@ compile_embind_tu() {
     local _src="$1" _obj="$2" _subdir="$3" _defines="${4:-}"
 
     local _includes="-I${KICAD_BUILD} -I${KICAD_DIR}/include -I${KICAD_DIR}/${_subdir} -I${KICAD_DIR}/common"
+    # The editor-frame headers the bindings reach into (libs 0019 F3: the
+    # Symbol Editor's open copy) live one level down, like eeschema's own
+    # CMake include list (./symbol_editor).
+    _includes+=" -I${KICAD_DIR}/${_subdir}/symbol_editor -I${KICAD_DIR}/${_subdir}/widgets"
     # Generated DSN-lexer headers (e.g. pcb_lexer.h, used transitively via kicad_clipboard.h →
     # pcb_io_kicad_sexpr_parser.h) are emitted into the common build subdir by make_lexer.
     _includes+=" -I${KICAD_BUILD}/common"