Add Workforce rota integration to HK Planner

Pulls HK staff shifts from Workforce.com API into the staff rota section.
Rota rows (read-only, WF badge, times+hours per day) appear above manual rows;
manual name inputs get a datalist populated from WF staff. Sync triggered via
button with stale-week detection. Dept selection stored per-app in CategorySettings.

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

backend/src/index.js

@@ -4,6 +4,7 @@ import cors from '@fastify/cors'
 import { initDb } from './db.js'
 import { bookingRoutes } from './routes/bookings.js'
 import { configRoutes } from './routes/config.js'
+import { workforceRoutes } from './routes/workforce.js'
 
 const app = Fastify({ logger: true, trustProxy: true })
 
@@ -14,6 +15,7 @@ app.get('/health', async () => ({ status: 'healthy' }))
 
 await app.register(bookingRoutes)
 await app.register(configRoutes)
+await app.register(workforceRoutes)
 
 try {
   await initDb()