Upload files directly to Supabase Storage via signed URLs, bypassing
the Next.js 100MB body size limit. Supports scans up to 200MB with
real-time progress tracking that persists across sidebar panel switches.
- Add Zustand upload store for persistent upload state
- Add createAssetUploadUrl/confirmAssetUpload server actions
- Add XHR-based upload orchestrator with progress events
- Scene node creation works even if sidebar panel unmounts
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>