feat: auto-populate department_id on create + seed default campus with backfill

apps/server/src/rooms/dto/room.dto.ts

@@ -27,6 +27,10 @@ export class CreateRoomDto {
   @IsOptional()
   @IsNumber()
   monthlyRate?: number;
+
+  @IsOptional()
+  @IsInt()
+  departmentId?: number;
 }
 
 export class UpdateRoomDto {

apps/server/src/rooms/rooms.service.ts

@@ -100,7 +100,9 @@ export class RoomsService {
   }
 
   async create(dto: CreateRoomDto) {
-    return this.repo.save(this.repo.create(dto));
+    const entity = this.repo.create(dto);
+    if (dto.departmentId) entity.departmentId = dto.departmentId;
+    return this.repo.save(entity);
   }
 
   async update(id: number, dto: UpdateRoomDto) {