fix(telemetry): record tool usage once centrally, sanitize raw tool names (#1073)

* fix(telemetry): record tool usage once centrally, sanitize raw tool names

* fix(telemetry): defer native MCP usage recording until validation passes

* fix(telemetry): narrow UseMcpToolTool callback, harden test mocks, close coverage gaps

* test(telemetry): complete native MCP mock so validateToolExists runs the real path