feat(gui2): Integrate mcp_client.py for native file tools

Wires up the mcp_client.perf_monitor_callback to the gui_2.py App class and verifies the dispatch loop through a newly created test.

gui_2.py

@@ -19,6 +19,7 @@ import tomllib
 import events
 import numpy as np
 import api_hooks
+import mcp_client
 from performance_monitor import PerformanceMonitor
 
 from imgui_bundle import imgui, hello_imgui, immapp
@@ -242,6 +243,7 @@ class App:
         ai_client.confirm_and_run_callback = self._confirm_and_run
         ai_client.comms_log_callback = self._on_comms_entry
         ai_client.tool_log_callback = self._on_tool_log
+        mcp_client.perf_monitor_callback = self.perf_monitor.get_metrics
 
         # AI client event subscriptions
         ai_client.events.on("request_start", self._on_api_event)