fix: room number + photos in task cards; time tracking for tasks

- Backend POST housekeeping: include photos in INSERT, return task with room JOIN
- Backend PATCH housekeeping: set started_at on in_progress, return task with room JOIN
- WS broadcasts now include room_number/assignee_name from JOIN
- Frontend: normalizeTask() helper maps snake_case WS fields to camelCase
- TechnicalPage: fix room number display (roomNumber || room_number)
- TechnicalPage: show time spent (started_at → completed_at) on task cards
- HousekeepingPage: history tab now includes maintenance reports (no category filter)
- HousekeepingPage: HistoryCard shows photos, notes, time spent, maintenance styling
- Migration 028: started_at TIMESTAMPTZ column on housekeeping_tasks
- types: add startedAt? to HousekeepingTask

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

backend/migrations/028_task_started_at.sql

@@ -0,0 +1 @@
+ALTER TABLE housekeeping_tasks ADD COLUMN IF NOT EXISTS started_at TIMESTAMPTZ;