refactor: remove dead export_gltf.py, cleanup rendering tasks, improve tessellation UI

- Remove export_gltf.py (Blender-based GLB export replaced by OCC direct)
- Remove unused export_gltf_for_order_line_task
- Add Ultra tessellation preset to Admin settings
- Improve tessellation preset descriptions and styling
- Minor cleanup across media, rendering, and workflow modules

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

frontend/src/api/media.ts

@@ -7,7 +7,6 @@ export type MediaAssetType =
   | 'stl_low'
   | 'stl_high'
   | 'gltf_geometry'
-  | 'gltf_production'
   | 'usd_master'
   | 'blend_production'