fix: Restore missing imports in Room3DViewer

frontend/src/components/facility3d/Room3DViewer.tsx

@@ -1,5 +1,10 @@
 import { PlantPosition } from './types';
-// ...
+import { Canvas } from '@react-three/fiber';
+import { OrbitControls, Environment, ContactShadows } from '@react-three/drei';
+import { RoomObject } from './RoomObject';
+import { Room3D } from '../../lib/layoutApi';
+import { useMemo } from 'react';
+
 interface Room3DViewerProps {
     room: any;
     visMode?: 'STANDARD' | 'HEALTH' | 'YIELD' | 'TEMP' | 'HUMIDITY';