perf: reduce 3D runtime artifacts (#7)

apps/viewer-3d/src/viewer/loaders.ts

@@ -1,8 +1,10 @@
 import * as THREE from 'three';
 import { GLTFLoader } from 'three/examples/jsm/loaders/GLTFLoader.js';
-import { DRACOLoader } from 'three/examples/jsm/loaders/DRACOLoader.js';
+import {
+  DRACOLoader,
+  DRACO_GLTF_CONFIG,
+} from 'three/examples/jsm/loaders/DRACOLoader.js';
 import { KTX2Loader } from 'three/examples/jsm/loaders/KTX2Loader.js';
-import { publicAssetUrl } from '../runtimeBase';
 
 export interface ViewerLoaders {
   gltf: GLTFLoader;
@@ -10,17 +12,14 @@ export interface ViewerLoaders {
   ktx2: KTX2Loader;
 }
 
-// SINGLETON — multiple DRACOLoader/KTX2Loader instances crash (three.js #22445).
-// Reuse across every load. Decoder WASM lives under public/draco + public/basis
-// (version-matched to the installed three.js).
+// 여러 DRACOLoader/KTX2Loader instance를 만들면 충돌할 수 있으므로 하나를 공유합니다.
+// decoder URL은 Three.js import가 생성하는 version 일치 hashed asset을 사용합니다.
 let _cache: ViewerLoaders | null = null;
 
 export function getLoaders(renderer: THREE.WebGLRenderer): ViewerLoaders {
   if (_cache) return _cache;
-  const draco = new DRACOLoader().setDecoderPath(publicAssetUrl('draco/'));
-  const ktx2 = new KTX2Loader()
-    .setTranscoderPath(publicAssetUrl('basis/'))
-    .detectSupport(renderer);
+  const draco = new DRACOLoader().setDecoderPath(DRACO_GLTF_CONFIG);
+  const ktx2 = new KTX2Loader().detectSupport(renderer);
   const gltf = new GLTFLoader().setDRACOLoader(draco).setKTX2Loader(ktx2);
   _cache = { gltf, draco, ktx2 };
   return _cache;