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>

backend/app/tasks/gpu_tasks.py

@@ -5,7 +5,7 @@ from app.tasks.celery_app import celery_app
 logger = logging.getLogger(__name__)
 
 
-@celery_app.task(name="app.tasks.gpu_tasks.probe_gpu", queue="thumbnail_rendering")
+@celery_app.task(name="app.tasks.gpu_tasks.probe_gpu", queue="asset_pipeline")
 def probe_gpu() -> dict:
     """Run Blender GPU probe on the render-worker. Stores result in system_settings."""
     import subprocess