Add Playwright test infrastructure for wxWidgets WASM port

- Add tests/ directory with Playwright e2e tests
- Add minimal wxWidgets WASM test application
- Add build script for test app (scripts/build-wasm-test.sh)
- Update wxWidgets submodule with WASM build fixes
- Update .gitignore for test artifacts

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

tests/package.json

@@ -0,0 +1,16 @@
+{
+  "name": "kicad-wasm-tests",
+  "version": "1.0.0",
+  "description": "Playwright tests for wxWidgets WASM port",
+  "scripts": {
+    "test": "playwright test",
+    "test:ui": "playwright test --ui",
+    "test:headed": "playwright test --headed",
+    "build-wasm": "cd wasm-app && make -f Makefile.wasm",
+    "serve": "npx serve wasm-app -p 8080"
+  },
+  "devDependencies": {
+    "@playwright/test": "^1.40.0",
+    "serve": "^14.2.0"
+  }
+}