Behavior: Transitions the schedule to a Stopping state and halts channel playback. When background mode is enabled (default), a batch action message is queued for asynchronous processing. When background mode is disabled, the channel is stopped synchronously.

Authorization: Requires a valid Bearer token.

Side Effects: The schedule status is updated to Stopping and a batch action message may be sent. The associated live channel stops playback.

Error Scenarios: Returns 400 if the schedule is not found or is already in a Stopped state. Returns 401 if the caller is not authenticated.