Add JWT authentication with animated login page

- Backend: JWT auth with /api/auth/login and /api/auth/verify endpoints
- Middleware: requireAuth protects all /api routes except /api/auth
- Frontend: Animated characters login page with eye-tracking effects
- Auth state persisted in localStorage with token verification on mount
- Sidebar logout button, 401 auto-logout, 30-day token expiry
- shadcn button, input, checkbox, label components added

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/package.json

@@ -15,6 +15,9 @@
     "vite": "^8.0.1"
   },
   "dependencies": {
+    "@radix-ui/react-checkbox": "^1.3.3",
+    "@radix-ui/react-label": "^2.1.7",
+    "@radix-ui/react-slot": "^1.2.3",
     "@tanstack/react-query": "^5.95.0",
     "@types/react": "^19.2.14",
     "@types/react-dom": "^19.2.3",
@@ -25,7 +28,7 @@
     "radix-ui": "^1.4.3",
     "react": "^19.2.4",
     "react-dom": "^19.2.4",
-"tailwind-merge": "^3.5.0",
+    "tailwind-merge": "^3.5.0",
     "tailwindcss-animate": "^1.0.7"
   }
 }