test: add E2E tests covering full user journeys

- Create tests/e2e/full-flow.spec.ts with 5 E2E scenarios
- Test home page navigation and layout
- Test game creation via form
- Test metadata search functionality
- Test ROM-to-game linking workflow
- Test complete user journey: create → search → link → view
- Configure Playwright for multi-browser testing (chromium, firefox, webkit)
- Optimize playwright.config.ts for E2E stability
- Total: 15 tests (5 scenarios × 3 browsers)

frontend/vite.config.ts

@@ -5,13 +5,14 @@ export default defineConfig({
   plugins: [react()],
   server: {
     port: 5173,
+    proxy: {
+      '/api': {
+        target: 'http://localhost:3000',
+        changeOrigin: true,
+        rewrite: (path) => path,
+      },
+    },
   },
-});
-import { defineConfig } from 'vite';
-import react from '@vitejs/plugin-react';
-
-export default defineConfig({
-  plugins: [react()],
   test: {
     environment: 'jsdom',
     globals: true,
@@ -19,10 +20,3 @@ export default defineConfig({
     include: ['tests/**/*.spec.tsx'],
   },
 });
-import { defineConfig } from 'vite';
-import react from '@vitejs/plugin-react';
-
-export default defineConfig({
-  plugins: [react()],
-  server: { port: 5173 },
-});