Improve feedback: notify user when no shape tool is active

Improve feedback: notify user when no shape tool is active: When a shape tool (e.g., rectangle, ellipse, diamond, arrow) is selected and then immediately deactivated by pressing Esc, the UI still gives the impression that the tool is active. However, attempting to draw on the canvas results in no action, and the user receives no feedback. This lack of feedback may confuse users who believe the shape tool is still active and functional.