startCountdown method
Starts a countdown with the given duration in minutes.
Implementation
void startCountdown(int minutes) {
// Stop any existing timer
_timer?.cancel();
remainingTime.value = minutes * 60; // Convert minutes to seconds
_timer = Timer.periodic(const Duration(seconds: 1), (timer) {
if (remainingTime.value > 0) {
remainingTime.value--;
} else {
timer.cancel(); // Stop the timer at 0
}
});
}