fix(3d-viewer): add missing THREE import to fix build error

frontend/src/pages/Facility3DViewerPage.tsx

@@ -1,6 +1,7 @@
 import { useEffect, useState, Suspense, useMemo, Component, ReactNode } from 'react';
 import { Canvas } from '@react-three/fiber';
 import { OrbitControls, Text, Instances, Instance, Html } from '@react-three/drei';
+import * as THREE from 'three';
 import { layoutApi, Floor3DData } from '../lib/layoutApi';
 import { Loader2, ArrowLeft } from 'lucide-react';
 import { Link } from 'react-router-dom';