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>