Improve countdown timer

[bukulu-am]

Summary

Enhanced the CountDown Timer with new features and improved UI.

Changes Made

• Visual progress bar that changes color (Green → Yellow → Red)
• Preset buttons (10s, 30s, 60s)
• Pause button toggles to "Resume" when paused
• Timer displays time in MM:SS format
• Improved UI with better colors and layout

Testing

• Preset buttons work correctly
• Progress bar updates during countdown
• Progress bar changes color at thresholds
• Pause button toggles to "Resume"
• Resume continues countdown
• Reset works correctly
• No bugs found

Checklist

• Code follows project style
• Tested locally
• No breaking changes

[github-actions]

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