fix: guard transient controls and verify timeline endpoints

artemis/controllers/unified_controller.py

@@ -245,8 +245,7 @@ class UnifiedMobileController:
         return await self._driver.input_text("", clear_existing=True)
 
     async def get_ui_elements(self) -> list[dict]:
-        screen_data = await self._driver.get_screen_data()
-        return screen_data.ui_elements or []
+        return await self._driver.get_ui_elements()
 
     async def get_screen_data(self) -> "ScreenDataResponse":
         """Get screen data including screenshot, UI hierarchy, dimensions, and platform."""