[FEAT] Add Export Functionality for Workout Routines

[FalkenDev]

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

I want to save or share my workout routines, but there is no way to export them from the app.

Describe the solution you'd like

I would like the ability to export all workout routines to a JSON file. The JSON file should include:

• Routine names
• Exercises in the routine
• Sets, reps, and weights for each exercise

This feature could be added to the "Workout Builder" section with an "Export" button.

Describe alternatives you've considered

Manually writing down my workout routines, but this is tedious and prone to errors.

Why is this feature important to you?

This feature would allow me to back up my workout routines and share them with others. It would also make it easier to migrate my data if I need to reinstall the app or move to a new device.

Additional context

None.

✅ 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.