[FEAT] Add Gamification (Badges and Achievements)

[FalkenDev]

Is your feature request related to a problem? Please describe.

I want to stay motivated by earning badges or achievements, but there is currently no gamification in the app.

Describe the solution you'd like

I would like a gamification system where I can:

• Earn badges for milestones (e.g., "First Workout," "100 Workouts Completed").
• Unlock achievements for specific goals (e.g., "Lifted 10,000 lbs in total").
• View my badges and achievements in a dedicated section.

Describe alternatives you've considered

Using external apps for gamification, but this doesn't integrate with my workout data.

Why is this feature important to you?

This feature would make the app more engaging and encourage consistency.

✅ Checklist

• I have searched the existing issues and have not found a similar feature request.
• I am willing to work on this feature myself. (Optional)
• I have read and agree to the project's Code of Conduct.