feat: implement storage quota management for uploads

- Added storage quota enforcement for audio and image uploads in the respective routes.
- Introduced reservation system to manage concurrent uploads and prevent quota overages.
- Enhanced comment creation to account for audio and image attachment sizes against user quotas.
- Created new UploadReservation model to track in-flight upload reservations.
- Backfilled existing video assets with size information from R2.
- Added progress component for UI feedback during uploads.
- Updated API responses to include reservation IDs for better quota management.
- Adjusted error handling to return appropriate storage limit exceeded messages.

AGENTS.md

@@ -14,6 +14,7 @@
 - Use `checkProjectAccess()` / `checkWorkspaceAccess()` for authorization instead of ad-hoc role checks.
 - For API responses, use `successResponse` / `apiErrors` from `@/lib/api-response`.
 - Keep API and UI imports on `@/` aliases when available.
+- In Prisma raw SQL, use `$executeRaw` for statements that return no rows (e.g. `pg_advisory_xact_lock`). Using `$queryRaw` on void-returning functions causes a Prisma deserialization error (`Failed to deserialize column of type 'void'`).
 
 ## Important locations
 - Custom SQL managed by Prisma migrations: `prisma/migrations/*/migration.sql`.