- Add BrainApiClient for interacting with Brain API storage endpoints
- Update MediaStreamInput to use storage_id + filename instead of presigned URLs
- Update MediaStreamOutput to use Brain API client for uploads and remove output_object_keys dependency
- Add environment configuration for Brain API connection
- Add test file for Brain API client functionality
This enables ComfyUI nodes to work with the new storage architecture
where Brain API acts as a proxy for MinIO operations.
