perf: reduce 3D runtime artifacts (#7)

apps/viewer-3d/docs/architecture.html

@@ -104,7 +104,7 @@
   <tr><td>지오메트리 압축</td><td>Draco</td><td>~73% 축소 검증됨</td></tr>
   <tr><td>텍스처 압축</td><td>WebP(런타임) / KTX2·Basis(고급)</td><td>KTX2는 별도 CLI 단계(<code>toktx</code>)</td></tr>
   <tr><td>빌드</td><td>Vite + TypeScript (strict)</td><td>three vendor + 포맷별 로더 청크 분리</td></tr>
-  <tr><td>디코더 호스팅</td><td><code>public/draco</code> + <code>public/basis</code> + <code>public/web-ifc</code></td><td>postinstall로 자동 복사</td></tr>
+  <tr><td>디코더 호스팅</td><td>Vite hashed Draco·Basis asset + <code>public/web-ifc</code></td><td>Three.js import로 생성, single-thread IFC WASM만 postinstall 복사</td></tr>
   <tr><td>에셋 파이프라인</td><td>gltf-transform + draco3d</td><td><code>tools/preprocess.mjs</code> (GLB 전용)</td></tr>
 </table>
 
@@ -122,13 +122,12 @@
     progress.ts           # showProgress/hideProgress/setProgress/setStatus
     fps.ts                # ★ 화면 FPS 오버레이 (EMA, 색상코딩)
 public/
-  draco/ basis/           # 디코더 WASM (자동 복사)
   web-ifc/                # ★ web-ifc.wasm (단일스레드, 자동 복사)
   samples/                # Box/Duck/Avocado/Duck.optimized + Cube.obj/dae/fbx/ifc
   previews/               # Duck.webp + Cube.{obj,dae,fbx,ifc}.webp (24프레임 360°)
 tools/
   preprocess.mjs          # gltf-transform Draco+WebP 압축 (GLB 전용)
-  copy-decoders.mjs       # postinstall: draco+basis+web-ifc 복사
+  copy-decoders.mjs       # postinstall: single-thread web-ifc WASM 복사
   prerender.mjs           # 360° 턴테이블 → Animated WebP (포맷 무관)
   perf-smoke.mjs          # 헤드리스 체감 로드 측정 (&lt;3s)
   adaptive-smoke.mjs      # ★ CPU 스로틀로 60fps↓ 강등 실증