refactor: establish unified viewer workspaces

apps/viewer-3d/tools/copy-decoders.mjs

@@ -2,14 +2,16 @@
 // runtime paths /draco/ and /basis/ resolve (version-matched to installed three).
 // Also copies the web-ifc single-thread WASM to public/web-ifc/ for the IFC path.
 // Runs automatically via `npm install` (postinstall). Safe to re-run.
-import { cpSync, copyFileSync, existsSync, mkdirSync } from 'node:fs';
+import { cpSync, copyFileSync, existsSync, mkdirSync, rmSync } from 'node:fs';
 import { dirname, resolve } from 'node:path';
 import { fileURLToPath } from 'node:url';
 
 const __dirname = dirname(fileURLToPath(import.meta.url));
 const root = resolve(__dirname, '..');
 
-const libs = resolve(root, 'node_modules/three/examples/jsm/libs');
+const threeEntry = fileURLToPath(import.meta.resolve('three'));
+const threeRoot = resolve(dirname(threeEntry), '..');
+const libs = resolve(threeRoot, 'examples/jsm/libs');
 const targets = [
   [resolve(libs, 'draco/gltf'), resolve(root, 'public/draco')],
   [resolve(libs, 'basis'), resolve(root, 'public/basis')],
@@ -25,13 +27,15 @@ for (const [src, dest] of targets) {
     console.warn(`[copy-decoders] source missing: ${src}`);
     continue;
   }
+  rmSync(dest, { force: true, recursive: true });
   mkdirSync(dest, { recursive: true });
   cpSync(src, dest, { recursive: true });
   console.log(`[copy-decoders] ${src} -> ${dest}`);
 }
 
 // web-ifc single-thread WASM (+ MT build if present) for the IFC load path.
-const ifcSrcDir = resolve(root, 'node_modules/web-ifc');
+const ifcEntry = fileURLToPath(import.meta.resolve('web-ifc'));
+const ifcSrcDir = dirname(ifcEntry);
 const ifcDest = resolve(root, 'public/web-ifc');
 if (existsSync(ifcSrcDir)) {
   mkdirSync(ifcDest, { recursive: true });