Add forecast occupancy logic for room availability range APIs

docs/API_REFERENCE.txt

@@ -1004,6 +1004,8 @@ ROOM TYPE + ROOMS + ROOM IMAGES
   What it does:
 
   - Returns free rooms in date range.
+  - Uses forecast logic for active stays: if `toAt` is null, occupancy is considered up to booking `expectedCheckOutAt` (if present).
+  - Active stays with no expected checkout are treated as occupied.
 
   Request body:
 
@@ -1031,6 +1033,7 @@ ROOM TYPE + ROOMS + ROOM IMAGES
   What it does:
 
   - Returns available rooms with average rate over date range.
+  - Uses same forecast occupancy logic as availability-range.
 
   Request body: