feat(wasm): kicad_editor — merge the pcbnew+eeschema kifaces into ONE bundle (Part 2)

All four editors (PCB / Footprint / Schematic / Symbol) are now runtime --frame
choices of a single kicad_editor.wasm (178 MB at -O1 vs 147+82 separate; shared
wx/common/boost linked once). One editor per page load, as before; frames pcb /
fpedit / sch / symedit.

- wasm/editor/: the merged executable target (single_top + both kiface library sets,
  whole-archive pcbcommon) + the safety-net focus-walk Kiface() dispatch TU. Gated by
  KICAD_WASM_MERGED_EDITOR (kicad submodule bump carries the fork side: per-engine
  Kiface/getter binding + ODR renames + dual-kiface launcher).
- wasm/bindings/: per-editor collab entries renamed pcbCollab*/schCollab* (JS names
  unchanged); duplicate kicadOpenFile/kicadCollabOnSave + shared-name registrations
  guarded behind KICAD_MERGED_EMBIND; new kicad_editor_embind.cpp registers each
  shared JS name once, dispatching on the live frame.
- Build: kicad_editor app (build wrapper, target case arms, 3-object embind compile
  with the ABI-critical flags, STUB_APP=pcbnew); docker/build.sh "all" =
  kicad_editor calculator pl_editor gerbview (pcbnew/eeschema stay as explicit debug
  apps); scripts/kicad/audit-merged-symbols.sh = repeatable ODR-collision audit (run
  on kicad bumps).
- Frontend: Bundle type (bundle ≠ tool); TOOL_BUNDLE maps all four editors to
  kicad_editor; explicit --frame tokens for pcbnew (pcb) and eeschema (sch); publish
  list = the 4 real bundles.
- Tests/CI: five harnesses load kicad_editor.js with explicit frame tokens;
  PCBNEW_FAMILY_SPECS renamed BIG_MODULE_SPECS + the 8 eeschema-family specs (they
  now boot the merged module — SpiderMonkey x86 CI OOM routing); frame-runtime spec
  covers all four frames from the one bundle.

Validated so far: frame-runtime 4/4 (each frame boots with the right title, no
aborts, no duplicate embind registration); 24-spec merged-module regression green;
3D raytracer renders. Known pre-existing failure: 3d-viewer title-bar drag deadlock,
fixed on main by 7630c7e (2N+8 pthread pre-warm) — picked up by the follow-up rebase.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/scripts/setup-kicad-wasm.sh

@@ -79,17 +79,17 @@ copy_app() {
 }
 
 found_any=0
-# symbol_editor / footprint_editor are NOT separate bundles: their harness HTMLs
-# (symbol_editor.html / footprint_editor.html) load the eeschema / pcbnew bundle
-# and select the frame at runtime via --frame (editor-unification).
-copy_app pcbnew           && found_any=1
-copy_app eeschema         && found_any=1
+# The four editors (pcbnew / eeschema / footprint_editor / symbol_editor) are ALL
+# served by the ONE merged kicad_editor bundle: their harness HTMLs load
+# kicad_editor.js and select the frame at runtime via --frame (editor-unification
+# Part 2).
+copy_app kicad_editor     && found_any=1
 copy_app calculator       && found_any=1
 copy_app pl_editor        && found_any=1
 copy_app gerbview         && found_any=1
 
 if [ "$found_any" -eq 0 ]; then
-    echo "Error: no pcbnew/eeschema/calculator/pl_editor/gerbview artifacts found in output/ or docker volume" >&2
+    echo "Error: no kicad_editor/calculator/pl_editor/gerbview artifacts found in output/ or docker volume" >&2
     exit 1
 fi