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/services/newbook_rates_client.py

@@ -129,6 +129,32 @@ class NewbookRatesClient:
 
         return sorted(categories.values(), key=lambda c: c["category_name"])
 
+    async def get_occupancy_report(self, from_date: date, to_date: date) -> List[Dict]:
+        """
+        Fetch the occupancy report (reports_occupancy) for a date range.
+
+        Returns a list of category objects, each with nested per-date
+        occupancy: {category_id, category_name, occupancy: {date: {available,
+        occupied, maintenance, allotted, revenue_gross, revenue_net}}}.
+        Single response, no pagination.
+        """
+        payload = self._get_auth_payload()
+        payload.update({
+            "period_from": f"{from_date.isoformat()} 00:00:00",
+            "period_to": f"{to_date.isoformat()} 23:59:59",
+        })
+
+        response = await self.client.post(
+            self._get_url("reports_occupancy"),
+            json=payload,
+            auth=(self.username, self.password)
+        )
+        response.raise_for_status()
+        data = response.json()
+        if not data.get("success"):
+            raise NewbookRatesError(f"Newbook occupancy report failed: {data.get('message')}")
+        return data.get("data") or []
+
     async def get_category_rates(
         self,
         category_id: str,