feat: photos for tech tasks, 3 priorities, remove cleaning status from context menu

- Remove 'Убирается' (cleaning) from manually selectable HK statuses in calendar context menu — it now only shows automatically when a task is in_progress
- Reduce priorities from 4 to 3: remove 'high', keep urgent/medium/low across context menu, tech tasks modal, and HousekeepingTask type
- Add photo upload to technical tasks: upload via camera button per task, display thumbnails with hover-to-remove, stored as TEXT[] in DB (migration 026)
- Fix HousekeepingPage WS handler to filter by category — no longer adds maintenance tasks to housekeeping board
- Add 'tasks' folder support to upload route

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

backend/src/routes/housekeeping.ts

@@ -92,7 +92,7 @@ const housekeeping: FastifyPluginAsync = async (fastify) => {
       const hotelId = await getHotelId(slug)
       if (!hotelId) return reply.code(404).send({ error: 'Hotel not found' })
 
-      const allowed = ['room_id','type','status','priority','assignee_id','notes','due_date','category']
+      const allowed = ['room_id','type','status','priority','assignee_id','notes','due_date','category','photos']
       const updates: string[] = []
       const values: unknown[] = []
       let idx = 1