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>

scripts/kicad/build-kicad_editor.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+# Build the merged KiCad editor (pcbnew + eeschema kifaces in ONE image) for
+# WebAssembly. The editor frame (PCB / Footprint / Schematic / Symbol) is chosen
+# at runtime via single_top.cpp's --frame flag (editor-unification Part 2).
+# Thin wrapper around build-kicad-target.sh — see that script for options.
+
+set -e
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+exec "${SCRIPT_DIR}/build-kicad-target.sh" kicad_editor "$@"