v1.1.0

Add namespace isolation with multi-namespace recall (v1.1.0)

- Namespace field on Record with serde backward compat (default: "default")
- store/recall/search accept namespace parameter for isolation
- Multi-namespace queries: namespace=["default", "sandbox"]
- Namespace guards: consolidation, auto-connect, co-activation, 2-hop walk
- New methods: list_namespaces(), move_record(), namespace_stats()
- MCP: namespace support for all store/recall/search tools
- 250 Rust + 148 Python tests passing

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>