feat: kicad_tools headless CLI

One merged node-WASM CLI (wasm/tools, 26.5MB) supersedes sym_convert +
pcb_convert: --convert-lib (absolutizes paths — fixes the legacy plugin's
silent empty output on relative paths), --lint (now full-parses .kicad_pcb
via the linked pcbnew parser), --erc, --netlist, --bom, --plot, --drc.
Registered as the only headless CLI app; ASYNCIFY=0 CLIs skip the
nanosleep→Asyncify yield shim and exit via _exit (dieted static dtors trap).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ADzCSeN3Q9DJL3YW2FZTXB

wasm/bindings/kicad_tools_embind.cpp

@@ -0,0 +1,9 @@
+// kicad_tools' "embind" object — deliberately embind-free, mirroring
+// sym_convert_embind.cpp / pcb_convert_embind.cpp (ysync 0009 size research).
+//
+// Both dieted kifaces reference exactly ONE editor-embind symbol:
+// kicadCollabOnSave (eeschema files-io.cpp / pcbnew files.cpp save paths —
+// neither executes headless, and both TUs are pruned from the diets anyway).
+// This no-op hook satisfies any remaining reference without rooting the
+// editor surface.
+extern "C" void kicadCollabOnSave( const char* /* aPath */ ) {}

wasm/bindings/sym_convert_embind.cpp

@@ -1,11 +0,0 @@
-// sym_convert's "embind" object — deliberately embind-free (ysync 0009 size
-// research, step (a)).
-//
-// The eeschema kiface references exactly ONE symbol from the editor's embind
-// TU: kicadCollabOnSave (files-io.cpp, called from SCH_EDIT_FRAME::SaveEEFile —
-// a path the headless converter never executes). Linking the real
-// eeschema_embind.o for that one symbol roots the ENTIRE editor surface from
-// .init_array (EMSCRIPTEN_BINDINGS takes the address of every bound function:
-// kicadOpenFile → frames/tools/dialogs, collab bridge, presence → GAL), which
-// GC cannot remove. This no-op hook satisfies the reference instead.
-extern "C" void kicadCollabOnSave( const char* /* aPath */ ) {}