Add Device/Video models, signaling WebSocket, device and content routes

- Prisma: Device model (Quest/Phone, online status, battery, storage,
  game/streaming/cortex state), Video model with likes, VideoLike
- Signaling WebSocket for SDP/ICE relay and device presence
- Device routes: list, status, delete
- Content routes: video CRUD with range-support streaming
- SignalingManager service for device socket registry and heartbeat

src/routes/signaling/websocket.ts

@@ -0,0 +1,33 @@
+import { FastifyPluginAsync } from 'fastify';
+import { verifyAccessToken } from '../../plugins/auth.js';
+import { SignalingManager } from '../../services/signaling-manager.service.js';
+
+export function createSignalingRoutes(signalingManager: SignalingManager): FastifyPluginAsync {
+  const signalingRoutes: FastifyPluginAsync = async (fastify) => {
+    // GET /signaling/ws?token=<accessToken>
+    fastify.get('/signaling/ws', { websocket: true }, async (socket, request) => {
+      const url = new URL(request.url, `http://${request.headers.host}`);
+      const token = url.searchParams.get('token');
+
+      if (!token) {
+        socket.send(JSON.stringify({ type: 'error', error: 'Missing token' }));
+        socket.close();
+        return;
+      }
+
+      let userId: string;
+      try {
+        userId = await verifyAccessToken(token);
+      } catch {
+        socket.send(JSON.stringify({ type: 'error', error: 'Invalid or expired token' }));
+        socket.close();
+        return;
+      }
+
+      request.log.info({ userId }, 'Signaling WebSocket connected');
+      await signalingManager.handleConnection(userId, socket);
+    });
+  };
+
+  return signalingRoutes;
+}