⏱️ TimerAdded Pomodoro and Custom timer modes.

• Implemented countdown, start/pause, work/break phases, and completion alerts.
  -Added custom duration input with validation.
  -Added timer selection screen with Pomodoro/Custom options.
  -Added custom timer UI with background, fonts, and styling.
  -Implemented draggable timer windows.
  -Currently working on the right-click Exit menu for the timer window.