Telemetry events emitted by Noizu.MCP.Client.

Every outbound request emits a request span using :start, :stop, or :exception under [:noizu_mcp, :client, :request, ...]. Tool calls and discovery requests mirror those stages under :tool and :discovery. Transport failures emit [:noizu_mcp, :client, :transport, :exception].

Start measurements contain :system_time; stop and request-exception measurements contain native-unit :duration. Metadata contains only safe routing, operation, status, and correlation fields. Request arguments, results, headers, authentication material, and raw error reasons are never included.