fix: enable before_ui_callback when api only mode (fixes #7984)

webui.py

@@ -341,6 +341,7 @@ def api_only():
     setup_middleware(app)
     api = create_api(app)
 
+    modules.script_callbacks.before_ui_callback()
     modules.script_callbacks.app_started_callback(None, app)
 
     print(f"Startup time: {startup_timer.summary()}.")