MCP 0.3.0-beta.3: workspace isolation

The local bridge requires explicit workspace/listener configuration, rejects redirects and verifies workspace identity. Chat forwarding is disabled pending a supported scoped authentication handoff. Advisory holds and receipts remain available. Source includes the receipt containment/action classification fixes already present in npm beta.2, and retired hosted endpoints are removed from server metadata.

Validation: 85 source tests and 29 packed regression tests passed. Registry artifact bytes match the inspected package. Existing installations need to update.