refactor: rename thumbnail_rendering queue to asset_pipeline

The queue handles far more than thumbnails: OCC tessellation, USD master
generation, GLB production, order line renders, and workflow renders.
asset_pipeline better reflects its role as the render-worker's primary queue.

Updated all references in: task decorators, celery_app.py, beat_tasks.py,
docker-compose.yml worker command, worker.py MONITORED_QUEUES, admin.py,
CLAUDE.md, LEARNINGS.md, Dockerfile, helpTexts.ts, test files,
and all .claude/commands/*.md skill files.

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

render-worker/scripts/export_step_to_usd.py

@@ -616,7 +616,10 @@ def main() -> None:
                 continue
 
             part_path = f"{node_path}/{part_key}"
-            mesh_path = f"{part_path}/Mesh"
+            # Name the Mesh prim after part_key so Blender imports it with the
+            # part name directly (Blender collapses single-child Xform+Mesh into
+            # just the Mesh object, using the mesh prim's leaf name as object name).
+            mesh_path = f"{part_path}/{part_key}"
 
             # ── Xform prim ────────────────────────────────────────────────
             xform = UsdGeom.Xform.Define(stage, part_path)