Closes the last gap in the one-way Hanzo control surface. IAM/KMS/PaaS
already had both CLI subcommands and MCP tools; S3 had neither.
- hanzo s3: buckets/mb/rb/ls/stat/rm/presign over hanzo_s3 (MinIO) client,
creds from env (inject from KMS, never plaintext). Registered in the
unified hanzo CLI alongside iam/kms/paas.
- hanzo-tools-s3: S3Tool MCP tool (same action-dispatch pattern as PaaSTool),
exported via the hanzo.tools entry point; s3 added to loader prefix map.
- uv workspace: map hanzo-cli/iam/kms/s3 + tools-s3 to local sources so the
unified CLI resolves on-disk packages (fixes hanzo_iam ImportError from a
stale published 1.29.0 wheel shadowing local 1.30.0).
Tests: 7 CLI + 14 MCP, all green.