fix(vitest): exclude e2e/ from unit test runs

Vitest was loading Playwright E2E specs from e2e/ directory, causing
OOM crashes during full test runs. Added 'e2e/**' to exclude list.

frontend/vite.config.ts

@@ -104,7 +104,7 @@ export default defineConfig({
       provider: 'v8',
       reporter: ['text', 'json-summary'],
       include: ['src/**/*.{ts,tsx}'],
-      exclude: ['src/test/**', 'src/**/*.d.ts', 'src/main.tsx'],
+      exclude: ['src/test/**', 'src/**/*.d.ts', 'src/main.tsx', 'e2e/**'],
     },
   },
 });