feat: multi-format 3D viewer with large-file OBJ streaming, Z-up, projection/outline UI

Three.js viewer supporting glb/gltf/obj/fbx/dae/ifc/ply via both server (SSR)
and drag&drop (CSR) paths.

- Streaming OBJ parser (src/viewer/objStream.ts) for files past the V8 max
  string length (>~1GB text) that OBJLoader can't handle; indexed geometry,
  per-vertex color from MTL Kd, float64 recenter baked in.
- In-viewer float64 recenter (objRecenter.ts) for huge CAD/survey coordinates
  (~1e8) so float32 vertex buffers keep precision (no cracked faces).
- Z-up right-handed world; Y-up formats rotated on load.
- OBJ+MTL+texture drag&drop (LoadingManager URL-modifier maps dropped images).
- OrbitControls ground-plane panning (road/rail alignment workflow).
- UI: Zoom Fit, perspective/orthographic toggle, feature-edge outline.
- DoubleSide for CAD OBJ; PLY mesh + point-cloud support.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tools/dnd-smoke.mjs

@@ -0,0 +1,84 @@
+#!/usr/bin/env node
+/**
+ * tools/dnd-smoke.mjs — CSR (Path B / drag&drop) load smoke.
+ *
+ * The per-format perf-smoke only exercised Path A (?model=). This drives the
+ * REAL local-file path: fetch each sample into a File, hand it to
+ * window.__viewer.loadLocalFile(file) (exactly what the dropzone does), and wait
+ * for hmw:ready. Catches the blob:-URL-has-no-extension class of bug.
+ *
+ * USAGE: node tools/dnd-smoke.mjs [--url URL] [--asset /samples/x ...]
+ *   (run `npm run build && npm run preview` first)
+ */
+import puppeteer from 'puppeteer-core';
+import { existsSync } from 'node:fs';
+
+const CHROME_CANDIDATES = [
+  'C:/Program Files/Google/Chrome/Application/chrome.exe',
+  'C:/Program Files (x86)/Google/Chrome/Application/chrome.exe',
+  'C:/Program Files (x86)/Microsoft/Edge/Application/msedge.exe',
+];
+function findBrowser() {
+  if (process.env.PUPPETEER_EXECUTABLE_PATH && existsSync(process.env.PUPPETEER_EXECUTABLE_PATH)) return process.env.PUPPETEER_EXECUTABLE_PATH;
+  for (const p of CHROME_CANDIDATES) if (existsSync(p)) return p;
+  return null;
+}
+function parseArgs(argv) {
+  const a = argv.slice(2); let url = 'http://127.0.0.1:4173'; const assets = [];
+  for (let i = 0; i < a.length; i++) {
+    if (a[i] === '--url') url = a[++i]; else if (a[i] === '--asset') assets.push(a[++i]);
+  }
+  if (!assets.length) assets.push('/samples/Box.glb', '/samples/Duck.glb', '/samples/Avocado.glb', '/samples/Cube.obj', '/samples/Cube.fbx', '/samples/Cube.dae', '/samples/Cube.ifc');
+  return { url, assets };
+}
+
+async function dropOne(page, base, asset) {
+  await page.goto(base, { waitUntil: 'domcontentloaded', timeout: 30000 });
+  await page.waitForFunction('window.__viewer != null', { timeout: 15000 });
+  try {
+    const res = await page.evaluate(async (assetPath) => {
+      const name = assetPath.split('/').pop();
+      const resp = await fetch(assetPath);
+      if (!resp.ok) return { ok: false, err: 'fetch ' + resp.status };
+      const blob = await resp.blob();
+      const file = new File([blob], name, { type: blob.type || 'application/octet-stream' });
+      const ready = new Promise((resolve) => {
+        const onErr = (e) => resolve({ ok: false, err: 'viewer error: ' + (e.detail || 'unknown') });
+        window.addEventListener('hmw:ready', () => resolve({ ok: true }), { once: true });
+        // surface our own onError via console; also time out below
+        window.__dndTimeout = setTimeout(() => resolve({ ok: false, err: 'timeout (no hmw:ready)' }), 20000);
+      });
+      window.__viewer.loadLocalFile(file);
+      return ready;
+    }, asset);
+    return { asset, ...res };
+  } catch (e) {
+    return { asset, ok: false, err: (e && e.message) || String(e) };
+  }
+}
+
+async function main() {
+  const o = parseArgs(process.argv);
+  const exe = findBrowser();
+  if (!exe) { console.error('[dnd-smoke] No Chrome/Edge found.'); process.exit(1); }
+  const browser = await puppeteer.launch({ executablePath: exe, headless: 'new', args: ['--no-sandbox', '--use-gl=swiftshader', '--enable-webgl', '--ignore-gpu-blocklist'] });
+  const page = await browser.newPage();
+  const errs = [];
+  page.on('console', (m) => { const t = m.text(); if (t.includes('load failed') || t.includes('Failed to load')) errs.push(t); });
+
+  console.log('[dnd-smoke] CSR drag&drop path, base=' + o.url);
+  const results = [];
+  for (const asset of o.assets) {
+    process.stdout.write('  drop ' + asset + ' ... ');
+    const r = await dropOne(page, o.url, asset);
+    results.push(r);
+    console.log(r.ok ? 'OK' : 'FAIL (' + r.err + ')');
+  }
+  await browser.close();
+
+  const failed = results.filter((r) => !r.ok);
+  console.log('\n[dnd-smoke] ' + (results.length - failed.length) + '/' + results.length + ' passed');
+  if (failed.length) { console.error('[dnd-smoke] FAILURES: ' + failed.map((f) => f.asset).join(', ')); process.exit(1); }
+  console.log('[dnd-smoke] all local drops load.');
+}
+main().catch((e) => { console.error('[dnd-smoke] Fatal: ' + (e && e.stack ? e.stack : e)); process.exit(1); });