feat: pl_editor WASM port + browser file dialog fixes

Brings up KiCad's pagelayout_editor (drawing-sheet editor) in the
browser, to roughly the same "boots, canvas visible, partially usable
in-session" level as the existing pcbnew/eeschema/calculator ports.

Build:
- docker/build.sh: add pl_editor to the unified app dispatch (case,
  subdir map, all-loop).
- scripts/kicad/build-kicad-target.sh: add pl_editor to the case;
  upstream target name pl_editor under source subdir pagelayout_editor.
- scripts/kicad/build-pl_editor.sh: 7-line thin wrapper matching the
  pcbnew/eeschema/calculator pattern.
- tests/scripts/setup-kicad-wasm.sh: copy_app pl_editor.

App glue:
- wasm/stubs/nl_pl_editor_plugin_stub.cpp: no-op SpaceMouse plugin so
  pl_editor_frame.cpp's NL_PL_EDITOR_PLUGIN symbols resolve. Mirrors
  nl_pcbnew_plugin_stub.cpp.
- tests/apps/kicad/pl_editor.html: browser shell. preRun creates
  /home/kicad and FS.chdir there so file dialogs land somewhere
  friendly instead of MEMFS root (/dev/, /proc/, etc.).

E2E coverage:
- tests/kicad/pl_editor.spec.ts: 5 tests — smoke (canvas, no abort),
  wizard, File menu has Open/Save As, file-dialog folder-navigation
  regression, canvas + toolbar metrics.
- tests/e2e/filedialog-folder-nav.spec.ts: wxWidgets-level twin of
  the regression test (exercises the underlying widget directly via
  the standalone filedialog_test app).

Submodule bumps:
- kicad → feature/pl-editor (WASM gating in pagelayout_editor's
  CMakeLists + navlib stub).
- wxwidgets → feature/pl-editor (wxGenericFileDialog::OnOk navigates
  into selected directories; wasm/mouse.cpp emits wxEVT_LEFT_DCLICK
  via timestamp-based double-click detection — the latter benefits
  every wxWidgets-WASM app).

See features/pl-editor/ for the design doc + per-repo diff patches.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/scripts/setup-kicad-wasm.sh

@@ -17,10 +17,12 @@ mkdir -p "$KICAD_TEST"
 
 # Map an app name to its inner CMake build subdirectory. Most apps share their
 # subdir name with the app name; pcb_calculator emits OUTPUT_NAME=calculator
-# but lives under the pcb_calculator/ subtree of the build dir.
+# but lives under the pcb_calculator/ subtree of the build dir, and pl_editor's
+# source lives under pagelayout_editor/.
 kicad_subdir_for() {
     case "$1" in
         calculator) echo "pcb_calculator" ;;
+        pl_editor)  echo "pagelayout_editor" ;;
         *)          echo "$1" ;;
     esac
 }
@@ -64,9 +66,10 @@ found_any=0
 copy_app pcbnew     && found_any=1
 copy_app eeschema   && found_any=1
 copy_app calculator && found_any=1
+copy_app pl_editor  && found_any=1
 
 if [ "$found_any" -eq 0 ]; then
-    echo "Error: no pcbnew/eeschema/calculator artifacts found in output/ or docker volume" >&2
+    echo "Error: no pcbnew/eeschema/calculator/pl_editor artifacts found in output/ or docker volume" >&2
     exit 1
 fi