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/playwright.config.ts

@@ -0,0 +1,29 @@
+import { defineConfig, devices } from '@playwright/test';
+
+export default defineConfig({
+  testDir: './e2e',
+  fullyParallel: true,
+  forbidOnly: !!process.env.CI,
+  retries: process.env.CI ? 2 : 0,
+  workers: process.env.CI ? 1 : undefined,
+  reporter: 'html',
+  timeout: 60000,  // WASM can be slow to load
+
+  use: {
+    baseURL: 'http://localhost:8080',
+    trace: 'on-first-retry',
+  },
+
+  projects: [
+    {
+      name: 'chromium',
+      use: { ...devices['Desktop Chrome'] },
+    },
+  ],
+
+  webServer: {
+    command: 'npx serve wasm-app -p 8080',
+    port: 8080,
+    reuseExistingServer: !process.env.CI,
+  },
+});