- New s3/sigv4.go: JWT → SigV4 converter proxy * Validates JWT via JWKS * Checks s3:read/s3:write permissions * Forwards requests to MinIO with SigV4 signature - Router: Add /v1/s3/* routing to S3Handler - Gateway main: Initialize S3Handler with MinIO credentials - Proxy: Add JWTValidator() getter for s3 handler - Env vars: MINIO_ENDPOINT, MINIO_ACCESS_KEY, MINIO_SECRET_KEY