Port occupancy sync + category ordering from the forecasting version

- Bookability showed no availability because newbook_occupancy_report_data
  was never populated: add reports_occupancy client method and
  sync_occupancy job, run before rates in both Sync Now and the daily
  schedule (single fast API call)
- Category order: default display_order to the Newbook category id on
  sync (was 0 → alphabetical), preserve manual order on re-sync, extend
  PATCH to accept display_order, add up/down reorder arrows in Settings

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backend/scheduler.py

@@ -73,6 +73,11 @@ async def run_scheduled_fetch_current_rates():
         # run_fetch_current_rates is a coroutine — await it directly;
         # run_in_executor would return the coroutine object unawaited
         from jobs.fetch_current_rates import run_fetch_current_rates
+        from jobs.sync_occupancy import run_sync_occupancy
+        try:
+            await run_sync_occupancy()
+        except Exception as e:
+            logger.warning(f"Occupancy sync failed (continuing with rates): {e}")
         await run_fetch_current_rates()
     else:
         logger.debug("Newbook current rates sync skipped (disabled)")