Ticket #74 PR #28 Review: pass_audit approved Add availability_updated_at to list_members MCP output. Clean 2-file change: - MCP controller: Added availability_status and availability_updated_at to output - Test: Verifies both fields are present with ISO 8601 format Implementation uses safe navigation operator (&.iso8601) for nil handling. Bonus fix: Also added availability_status which was previously missing from output.