spec(harnessx-removal): memory store on MinIO -- metadata, S3 Select JSON queries, versioned provenance

Maintainer: use MinIO features including its JSON support; a server exists.
One MemoryStore interface with FileStore (laptop, tests) and MinioStore (the
store of record for the separate Kubernetes deployment): tags for indexing,
S3 Select pushed-down queries probed with a local fallback, versioning for
proposal provenance, lifecycle for raw outputs, presigned URLs and bucket
notifications kept for the follow-on that removes the host receiver.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01EmM1j46qgKMh3zqD1QMwEo

.kiro/specs/harnessx-removal/tasks.md

@@ -13,7 +13,10 @@ and passed its fixture test. Every task is a commit gated on the full suite's ow
   - _Requirements: 3.1, 5.1_
 
 - [ ] 2. Memory store and the `remember` task
-  - `plane/memory.py` (JSON rows per repository + pin, facts by content hash, ingest refuses below 1 GiB free),
+  - `plane/memory.py`: the `MemoryStore` interface with `FileStore` and `MinioStore` (object metadata/tags,
+    S3 Select JSON queries probed with a local fallback, versioned provenance, lifecycle, presign stubs;
+    `OUSAST_MEMORY` selects; MinIO settings from `.env`; `minio` SDK as an optional extra); JSON rows per
+    repository + pin, facts by content hash, `FileStore` ingest refuses below 1 GiB free,
     `plane/tasks/remember.py` (model-free), `reconciler.mark_done` under the run lock, seed and ingest wiring in
     `cli._plane`, generator annotations; fact reuse when repository, pin, candidate set and runner image match.
   - Fixture tests: rows from a recorded Run, reuse on an unchanged pin, recompute on a changed one, disk refusal.