Display a continue button when stopped

Relates to #216 This change adds a continue button to the timespan UI, which is only visible when items are not active. <img width="1133" height="389" alt="image" src="https://github.com/user-attachments/assets/c093f2c8-4574-4086-9c38-80d0df55e9e0" /> <img width="438" height="885" alt="image" src="https://github.com/user-attachments/assets/49b96ffc-185e-44ea-a3af-a17319551539" />