feat(gmsh): GMSH Frontal-Delaunay tessellation for clean cylinder seams

- Per-solid iteration prevents OOM on multi-part assemblies (25-part bearing:
  2.3GB RAM when processing compound → ~100MB per solid with per-solid approach)
- Fix CharacteristicLengthMax multiplier 5× → 15× and cap MinimumCirclePoints
  at 20 (prevents 63-pts/circle on angular_deflection=0.1rad → 231MB → 21MB)
- Geometry task timeout 120s → 600s for large assemblies
- Production task: reuse _geometry.glb when GMSH enabled (no re-tessellation)
  and cache _production_geom.glb for OCC (mtime vs STEP check)
- Viewer now prefers production GLB when available (shows correct GMSH mesh)
- GMSH OpenMP multithreading (min(cpu_count,16)) for 4.4× speedup

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/components/cad/InlineCadViewer.tsx

@@ -239,7 +239,10 @@ export default function InlineCadViewer({
   const hasProduction = (productionAssets?.length ?? 0) > 0
 
   useEffect(() => {
-    if (!hasGeometry && hasProduction) setGlbSource('production')
+    // Prefer production GLB when available — it has correct materials and a clean
+    // GMSH mesh. Fall back to geometry GLB only when no production GLB exists yet.
+    if (hasProduction) setGlbSource('production')
+    else setGlbSource('geometry')
   }, [hasGeometry, hasProduction])
 
   const activeDownloadUrl =