feat: workstations API + agent WebSocket — паркинг агентов и управление оборудованием

- migration 041: таблицы workstations, agent_pair_codes, workstation_devices
- routes/workstations: CRUD рабочих мест, генерация 6-значного кода, CRUD устройств
- POST /api/agent/pair: сопряжение агента по коду → JWT токен
- agent-ws.ts: WebSocket /ws/agent для постоянного соединения агентов,
  heartbeat 30s, онлайн/оффлайн статус в БД

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

backend/src/app.ts

@@ -33,6 +33,8 @@ import notificationsRoutes from './routes/notifications'
 import scheduleRoutes      from './routes/schedule'
 import loyaltyRoutes       from './routes/loyalty'
 import chatRoutes          from './routes/chat'
+import workstationRoutes   from './routes/workstations'
+import { setupAgentWsRoute } from './agent-ws'
 import { startJobs } from './jobs'
 
 export async function buildApp() {
@@ -111,6 +113,8 @@ export async function buildApp() {
   await fastify.register(scheduleRoutes)
   await fastify.register(loyaltyRoutes)
   await fastify.register(chatRoutes)
+  await fastify.register(workstationRoutes)
+  setupAgentWsRoute(fastify)
 
   startJobs()