Replaying and exiting earlier missions removes access to the next mission.

[thkruz]

We are clearing the Supabase progress, but not preserving some kind of "previously completed" flag for bypassing the prerequisite missions.

[thkruz]

Changed the code to update user progress rather than delete it when hitting "Play Again". This clears the completed objectives but retains the completion date. Made changes to the Scenario Selection page UI to sync with this new configuation.

Ready for production - closing this issue.