refactor: collapse dual-mode plumbing — the DOM port is the only WASM build

The canvas (wxUniversal) mode is gone (wxwidgets submodule); remove every
piece of side-by-side plumbing so there is exactly one build and one test
flow:

- scripts/build-wxuniversal-wasm.sh -> scripts/build-wx-wasm.sh; no
  --dom/--enable-universal; builds into build-wasm/wxwidgets
- build-wasm-test.sh: no DOM_BUILD / apps-dom rsync mirror / PORT=dom;
  apps build straight into tests/apps (Makefile.wasm PORT conditionals
  collapsed; wx.js + wx-dom.js always pre-js)
- docker/build.sh, build-kicad-target.sh, env.sh: WX_PORT / -dom /
  -universal suffixes removed; kicad builds to kicad-<app>, outputs to
  output/; wx.js/wx-dom.js copied from the real source path
  (/workspace/wxwidgets/build/wasm — the old build-wasm path never
  existed and silently failed)
- setup-kicad-wasm.sh: single target dir; the perl wx-dom.js injection is
  gone — the 7 checked-in kicad pages now reference wx-dom.js directly
- playwright configs serve apps/; fixtures drop the test-results/dom and
  logs/wxwidgets/dom namespacing; boot.spec asserts wxDomPort
  unconditionally; pcbnew.spec uses one reference image;
  appearance.spec assertions unconditional
- compare/update-baseline-screenshots.sh: --port removed
- tests/gal-regression/wasm/Makefile: links build-wasm/wxwidgets and
  carries wx-dom.js as a second pre-js — the gal-webgl suite (30 specs)
  now actually builds and runs here (it needed host-side boost+glm via
  scripts/deps; the bundle had been missing, timing the whole spec out)
- tests: clickCanvas() dispatches via page.mouse (DOM widgets
  legitimately cover the canvas; locator actionability refused the
  click); the comprehensive spec drives wxChoice through its native
  <select> (browser-owned popup cannot be coordinate-clicked)
- docs: README/CLAUDE.md/build.md script names and dirs;
  features/wx-dom-port README reframed (DOM is THE port), visual-notes
  bugs 26-28; FindwxWidgets.cmake config label drops 'wasmuniv'
- wxwidgets submodule -> 9dbacc9448 (DOM-only port, fork diff shrunk)

Gate: full wx e2e suite 292 passed / 1 skipped / 0 failed — first run
ever with the gal-webgl specs green (28 scenarios + load + sequential).

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

scripts/kicad/build-kicad-target.sh

@@ -75,17 +75,9 @@ source "${SCRIPT_DIR}/../common/stages.sh"
 KICAD_DIR="${PROJECT_ROOT}/kicad"
 WASM_LAYER="${PROJECT_ROOT}/wasm"
 
-# WX_PORT=dom links against the DOM (non-universal) wxWidgets build and
-# keeps its KiCad build tree separate from the canvas one.
-if [ "${WX_PORT:-}" = "dom" ]; then
-    KICAD_BUILD="${BUILD_ROOT}/kicad-${APP_NAME}-dom"
-    KICAD_STAMP="${BUILD_ROOT}/stamps/kicad-${APP_NAME}-dom.stamp"
-    WX_BUILD="${BUILD_ROOT}/wxwidgets-dom"
-else
-    KICAD_BUILD="${BUILD_ROOT}/kicad-${APP_NAME}"
-    KICAD_STAMP="${BUILD_ROOT}/stamps/kicad-${APP_NAME}.stamp"
-    WX_BUILD="${BUILD_ROOT}/wxwidgets-universal"
-fi
+KICAD_BUILD="${BUILD_ROOT}/kicad-${APP_NAME}"
+KICAD_STAMP="${BUILD_ROOT}/stamps/kicad-${APP_NAME}.stamp"
+WX_BUILD="${BUILD_ROOT}/wxwidgets"
 
 # Parse arguments - incremental build by default (optimized for development)
 NO_CLEAN=1
@@ -167,7 +159,7 @@ if [ $FULL_CLEAN -eq 1 ]; then
     log_info "Full clean: removing all stamps and build directories..."
     rm -rf "${STAMPS_DIR}"/*
     rm -rf "${BUILD_ROOT}/deps"/*
-    rm -rf "${BUILD_ROOT}/wxwidgets-universal"
+    rm -rf "${BUILD_ROOT}/wxwidgets"
     rm -rf "${BUILD_ROOT}/stubs"
     rm -rf "${KICAD_BUILD}"
     rm -rf "${SYSROOT}"/*
@@ -196,7 +188,7 @@ fi
 # Step 4: Build wxWidgets (incremental - only recompiles changed files)
 kw_stage wxwidgets
 log_info "Building wxWidgets..."
-"${SCRIPT_DIR}/../build-wxuniversal-wasm.sh" --no-clean
+"${SCRIPT_DIR}/../build-wx-wasm.sh" --no-clean
 
 log_info "Building KiCad ${APP_NAME} ${KICAD_VERSION} for WASM..."