feat: implement QR code scan login system with admin control

- Add scan login service with Redis-based token management
- Add scan login API routes for token generation and validation
- Add QRCodeLogin component for PC-side QR code display
- Add EntryQRCode component for mass login scenarios
- Add ScanLoginView for mobile-side login form
- Add localStorage persistence for user identity
- Add logout functionality to mobile client
- Add auto-redirect for logged-in users
- Add admin console control for QR code display on big screen
- Add socket event forwarding from admin to screen display

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/server/package.json

@@ -29,6 +29,7 @@
     "express": "^4.21.2",
     "helmet": "^8.0.0",
     "ioredis": "^5.4.2",
+    "jsonwebtoken": "^9.0.3",
     "multer": "^2.0.2",
     "nanoid": "^5.0.9",
     "pino": "^9.6.0",
@@ -42,6 +43,7 @@
     "@types/compression": "^1.7.5",
     "@types/cors": "^2.8.17",
     "@types/express": "^5.0.0",
+    "@types/jsonwebtoken": "^9.0.10",
     "@types/multer": "^2.0.0",
     "@types/uuid": "^11.0.0",
     "artillery": "^2.0.28",