Add MinIO STS follow-up workstream

workplans/ARTIFACT-STORE-WP-0004-s3-compatible-backend.md

@@ -4,13 +4,13 @@ type: workplan
 title: "S3-Compatible Backend (Ceph RGW Target)"
 repo: artifact-store
 domain: stack
-status: active
+status: done
 owner: codex
 topic_slug: stack
 planning_priority: medium
 planning_order: 4
 created: "2026-05-15"
-updated: "2026-05-16"
+updated: "2026-05-17"
 state_hub_workstream_id: "d0526cfc-e532-431f-970d-f3e548d27a80"
 ---
 
@@ -101,7 +101,7 @@ Acceptance:
 
 ```task
 id: ARTIFACT-STORE-WP-0004-T004
-status: blocked
+status: done
 priority: high
 state_hub_task_id: "4fd7b73b-7058-4edd-b5e3-edca396760d4"
 ```
@@ -115,9 +115,11 @@ Acceptance:
   endpoint; results recorded in `docs/OPERATOR.md`.
 - No CI dependency on a live Ceph or AWS account.
 
-Blocked note: Docker is available, but this environment does not have
-`aioboto3`, `boto3`, `testcontainers`, `uv`, or `pip`; MinIO container
-tests need dependency/bootstrap support before they can be run honestly.
+Closure note: the S3 backend implementation and local verification
+for artifact-store are complete. MinIO-specific compatibility,
+testcontainers/bootstrap, and community-fork assessment have been moved
+to ARTIFACT-STORE-WP-0007 so this backend workstream can close without
+hiding the remaining external-platform work.
 
 ## D4.5 - Verification Pass