fix(mcp): configure mcp_client allowlist on project switch

Previously mcp_client.configure() was only called during ai_client.send()
which meant GUI buttons (Slices/Inspect) couldn't access files when
project was switched to an external project like gencpp. Now _switch_project
reconfigures mcp_client with the new project's root and file_items.

config.toml

@@ -23,7 +23,7 @@ separate_tool_calls_panel = false
 bg_shader_enabled = false
 crt_filter_enabled = false
 separate_task_dag = false
-separate_usage_analytics = false
+separate_usage_analytics = true
 separate_tier1 = false
 separate_tier2 = false
 separate_tier3 = false