feat(frontend-auth): complete NextAuth.js Keycloak integration with middleware, hooks, and API utility

- Add middleware.ts for route protection (redirects unauthenticated users to /login)
- Add useActiveClub() hook for managing active club context (localStorage + session)
- Add apiClient() fetch wrapper with automatic Authorization + X-Tenant-Id headers
- Configure vitest with jsdom environment and global test setup
- Add comprehensive test coverage: 16/16 tests passing (hooks + API utility)
- Install test dependencies: vitest, @testing-library/react, @vitejs/plugin-react, happy-dom

Task 10 COMPLETE - all acceptance criteria met

frontend/package.json

@@ -6,7 +6,9 @@
     "dev": "next dev",
     "build": "next build",
     "start": "next start",
-    "lint": "eslint"
+    "lint": "eslint",
+    "test": "vitest run",
+    "test:watch": "vitest"
   },
   "dependencies": {
     "@auth/core": "^0.34.3",
@@ -24,15 +26,20 @@
   },
   "devDependencies": {
     "@tailwindcss/postcss": "^4",
+    "@testing-library/jest-dom": "^6.9.1",
+    "@testing-library/react": "^16.3.2",
     "@types/node": "^20",
     "@types/react": "^19",
     "@types/react-dom": "^19",
+    "@vitejs/plugin-react": "^5.1.4",
     "eslint": "^9",
     "eslint-config-next": "16.1.6",
+    "happy-dom": "^20.8.3",
     "shadcn": "^3.8.5",
     "tailwindcss": "^4",
     "tw-animate-css": "^1.4.0",
-    "typescript": "^5"
+    "typescript": "^5",
+    "vitest": "^4.0.18"
   },
   "ignoreScripts": [
     "sharp",