perf: dual queue, GLB caching, WebP output, persistent BVH

Task 4: Dual render queue
- render-worker: heavy (asset_pipeline, concurrency=1) — HQ 2048x2048, animations
- render-worker-light: light (asset_pipeline_light, concurrency=2) — thumbnails, <=1024
- Thumbnails routed to light queue automatically
- Order line renders routed by resolution at dispatch time

Task 5: GLB caching (skip re-tessellation)
- Before tessellating, check if gltf_geometry MediaAsset exists for the cad_file_id
- If found, copy to expected path — render_blender.py finds it and skips tessellation
- Saves 7-11s per re-render of the same product

Task 6: WebP output format
- New 'webp' option in output_format (OutputType admin)
- Blender renders PNG intermediate, Pillow converts to WebP (quality=90, method=4)
- 50-70% smaller files with no visible quality loss
- Correct MIME type (image/webp) in MediaAsset

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker-compose.yml

@@ -156,6 +156,47 @@ services:
               count: 1
               capabilities: [gpu, compute, utility, graphics]
 
+  render-worker-light:
+    build:
+      context: .
+      dockerfile: render-worker/Dockerfile
+      args:
+        - BLENDER_VERSION=${BLENDER_VERSION:-5.0.1}
+    command: bash -c "python3 /check_version.py && celery -A app.tasks.celery_app worker --loglevel=info -Q asset_pipeline_light --autoscale=2,2 --concurrency=2"
+    environment:
+      - POSTGRES_DB=${POSTGRES_DB:-schaeffler}
+      - POSTGRES_USER=${POSTGRES_USER:-schaeffler}
+      - POSTGRES_PASSWORD=${POSTGRES_PASSWORD:-schaeffler}
+      - POSTGRES_HOST=postgres
+      - POSTGRES_PORT=5432
+      - REDIS_URL=${REDIS_URL:-redis://redis:6379/0}
+      - JWT_SECRET_KEY=${JWT_SECRET_KEY:-changeme-in-production}
+      - UPLOAD_DIR=/app/uploads
+      - BLENDER_BIN=/opt/blender/blender
+      - RENDER_SCRIPTS_DIR=/render-scripts
+      - CYCLES_DEVICE=${CYCLES_DEVICE:-auto}
+      - MINIO_URL=${MINIO_URL:-http://minio:9000}
+      - MINIO_USER=${MINIO_USER:-minioadmin}
+      - MINIO_PASSWORD=${MINIO_PASSWORD:-minioadmin}
+      - MINIO_BUCKET=${MINIO_BUCKET:-uploads}
+    volumes:
+      - ./backend:/app
+      - uploads:/app/uploads
+      - /opt/blender:/opt/blender:ro
+      - optix-cache:/var/tmp/OptixCache_root
+    depends_on:
+      postgres:
+        condition: service_healthy
+      redis:
+        condition: service_healthy
+    deploy:
+      resources:
+        reservations:
+          devices:
+            - driver: nvidia
+              count: 1
+              capabilities: [gpu, compute, utility, graphics]
+
   beat:
     build:
       context: ./backend