S3 support

ObjectStore implements a subset of the S3 API. Unsupported operations and Amazon-specific headers are rejected. Check the v0.0.8 README checklist for the full list for this release.

Supported areas include object reads and writes, bucket creation and listing, multipart uploads, presigned URLs, signed streaming uploads, object copies, user metadata, tags, checksums, versioning, and basic ACL grants.

Not yet supported: bucket policies, IAM-style permissions, temporary credentials, lifecycle expiration, MFA Delete, and full AWS ACL ownership controls. The API subset does not imply production readiness.

ObjectStore also has a signed GET /_objectstore/capabilities endpoint. It reports the running server's software version, storage mode, operations, and configured limits. This is an ObjectStore extension, not an AWS S3 endpoint.