fix(website): resolve @opennextjs/cloudflare and test configuration issues

- Successfully installed @opennextjs/cloudflare v1.15.1
- Fixed Vitest configuration to exclude e2e tests
- Renamed e2e test files from .spec.ts to .e2e.ts to avoid Bun test runner conflicts
- Updated eslint.config.mjs and playwright.config.ts
- All tests passing: Vitest (1/1), Playwright (6/6)
- Production bundle size: ~5MB < 10MiB limit
- Marked TODO 0 complete in plan

website/vitest.config.ts

@@ -9,7 +9,7 @@ export default defineConfig({
     globals: true,
     setupFiles: [],
     include: ['src/**/*.{test,spec}.{js,mjs,cjs,ts,mts,cts,jsx,tsx}'],
-    exclude: ['e2e/**/*', 'node_modules/**/*'],
+    exclude: ['**/node_modules/**', '**/e2e/**', '**/.next/**'],
     alias: {
       '@': path.resolve(__dirname, './src'),
     },