Persist the "Debug details" toggle in the layout .ini

The View-menu verbosity switch reset to off on every launch. Register a
custom ImGui settings handler (a [CoopUI][State] section in coop_layout.ini,
alongside the window layout) so the operator's choice survives restarts.
Toggling it marks settings dirty so ImGui's auto-save writes it back.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

host/src/main.cpp

@@ -152,6 +152,9 @@ int run()
 	bool show_overlay = true;
 	double overlay_hidden_at = 0.0;
 	coop::UiState ui;
+	// Persist the "Debug details" verbosity in the .ini. Register before the first
+	// begin_frame() below, which is when ImGui loads the .ini and replays our handler.
+	coop::register_ui_settings(ui);
 	coop::FrameStats stats;
 
 	// Frame-sync: the hook generation we last presented (so we wait for the next one).