Default room image order fields to 0

src/main/kotlin/com/android/trisolarisserver/controller/RoomImages.kt

@@ -85,8 +85,8 @@ class RoomImages(
             sizeBytes = stored.sizeBytes,
             roomTypeCode = room.roomType.code,
             tags = tags?.toMutableSet() ?: mutableSetOf(),
-            roomSortOrder = roomSortOrder,
-            roomTypeSortOrder = roomTypeSortOrder
+            roomSortOrder = roomSortOrder ?: 0,
+            roomTypeSortOrder = roomTypeSortOrder ?: 0
         )
         return roomImageRepo.save(image).toResponse(publicBaseUrl)
     }

src/main/kotlin/com/android/trisolarisserver/controller/dto/RoomDtos.kt

@@ -40,8 +40,8 @@ data class RoomImageResponse(
     val contentType: String,
     val sizeBytes: Long,
     val tags: Set<String>,
-    val roomSortOrder: Int?,
-    val roomTypeSortOrder: Int?,
+    val roomSortOrder: Int,
+    val roomTypeSortOrder: Int,
     val createdAt: String
 )