Apply Unfold theme to DRF Token, Celery Beat, and Allauth models

[Pallavrai]

Changes

Applied Unfold admin theme styling to third-party package models:

• DRF Authentication: TokenProxy model
• Django Celery Beat: PeriodicTask, IntervalSchedule, CrontabSchedule, SolarSchedule, ClockedSchedule
• Django Allauth: SocialAccount, SocialApp, SocialToken

What was done

• Unregistered default admin classes for these models
• Re-registered with Unfold's ModelAdmin to apply dark theme styling
• Maintained all default functionality while providing consistent UI across admin panel

Benefits

• All admin models now have consistent modern dark theme
• Improved visual experience when managing background tasks and social authentication

Before:

After:

Closes #29

[Pallavrai]

Hey @DimitrovK, this is my final PR for #29 . I think the admin panel looks good now. If you’d like any further customizations—such as an improved sidebar with more meaningful names for each task instead of the default old admin panel options feel free to let me know.

[DimitrovK]

Good job!