feat: terminate agent socket and send unpair on workstation delete

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

backend/src/routes/workstations.ts

@@ -16,7 +16,7 @@
 import { FastifyPluginAsync } from 'fastify'
 import { db } from '../db'
 import crypto from 'crypto'
-import { sendCommand, sendCommandAndWait } from '../agent-ws'
+import { sendCommand, sendCommandAndWait, getAgentSocket } from '../agent-ws'
 
 type SlugParam = { Params: { slug: string } }
 type WsParam   = { Params: { slug: string; id: string } }
@@ -106,6 +106,13 @@ const workstationRoutes: FastifyPluginAsync = async (fastify) => {
       if (!canManage(req.user.hotelSlug, req.user.role, slug))
         return reply.code(403).send({ error: 'Forbidden' })
 
+      // Notify agent to unpair, then terminate the socket
+      const socket = getAgentSocket(id)
+      if (socket) {
+        try { socket.send(JSON.stringify({ type: 'unpair' })) } catch { /* ignore */ }
+        setTimeout(() => socket.terminate(), 500)
+      }
+
       await db.query('DELETE FROM workstations WHERE id = $1', [id])
       return reply.code(204).send()
     },