fix: add YAML frontmatter to RA-H OS Custodianship Contract

- Added required frontmatter block with kind=pattern, name, and description
- Fixes CI validate step that was blocking the PR pipeline
- All other CI checks (lint, ai-review) were skipped due to validate failure

ra-h-os-custodianship-contract.prose.md

@@ -1,3 +1,14 @@
+---
+kind: pattern
+name: ra-h-os-custodianship-contract
+description: >
+  Operational standards for maintaining RA-H OS as a high-functioning shared
+  memory system across all agents. Defines rules for embedding consistency,
+  namespace discipline, staleness management, orphan prevention, agent
+  custodianship, and recovery protocols. Prevents knowledge graph degradation
+  and ensures reliable semantic search capabilities.
+---
+
 # RA-H OS Custodianship Contract — Shared Memory Protocol
 
 ## Purpose