fix: GCS S3 interop returns NotImplemented for DeleteObjects batch delete

[ameyanaik11]

Bug report

• I confirm this is a bug with Supabase, not with my own application.
• I confirm I have searched the Docs, GitHub Discussions, and Discord.

Describe the bug

When using Google Cloud Storage (GCS) via its S3 interoperability API as the storage backend, deleting objects from the Supabase UI (or any call to the batch delete endpoint) fails with a NotImplemented error.

GCS S3 interop does not support the DeleteObjects (multi-object batch delete) API. The storage-api's S3Backend.deleteObjects() always uses DeleteObjectsCommand, so all deletes fail.

To Reproduce

1. Configure Supabase Storage with GCS in S3 interoperability mode as the backend (GLOBAL_S3_ENDPOINT, GLOBAL_S3_REGION, GCS HMAC credentials)
2. Upload a file via Supabase Studio or the API
3. Try to delete the file from Studio UI (or call DELETE /object/bulk / batch delete endpoint)
4. Observe HTTP 400 with NotImplemented error

Error in storage-api logs:

NotImplemented: A header or query you provided requested a function that is not implemented.

Expected behavior

Files should be deleted successfully. Individual DeleteObject calls work correctly on GCS — only the batch DeleteObjects API is unsupported.

Screenshots

System information

• OS: Linux (GKE)
• Version of supabase storage-api: v1.37.8
• Storage backend: Google Cloud Storage (S3 interoperability mode)

Additional context

• Individual DELETE /object/:bucket/:path (single delete) works correctly as it uses DeleteObjectCommand under the hood
• Batch delete via Studio UI fails because it calls DeleteObjectsCommand which GCS does not implement
• Fix proposed in fix: fall back to individual deletes when S3 backend returns NotImplemented for DeleteObjects #899: catch NotImplemented and fall back to sequential individual DeleteObjectCommand calls