Add MCP server context to otel tool_result logs (#12267)

Summary
- capture the origin for each configured MCP server and expose it via
the connection manager
- plumb MCP server name/origin into tool logging and emit
codex.tool_result events with those fields
- add unit coverage for origin parsing and extend OTEL tests to assert
empty MCP fields for non-MCP tools
- currently not logging full urls or url paths to prevent logging
potentially sensitive data

Testing
- Not run (not requested)

codex-rs/otel/tests/suite/runtime_summary.rs

@@ -44,6 +44,8 @@ fn runtime_metrics_summary_collects_tool_api_and_streaming_metrics() -> Result<(
         true,
         "ok",
         &[],
+        None,
+        None,
     );
     manager.record_api_request(1, Some(200), None, Duration::from_millis(300));
     manager.record_websocket_request(Duration::from_millis(400), None);