Add room scoring and win/loss counters

Rooms should support a simple scoring mode that tracks who is winning across rounds, not just individual solve times.

Feedback source:
- Add ability to see session average to see who is winning overall in the room.
- Scoring system that displays amount of rounds/solves won.
- Win/loss counter mode would be cool.
- Maybe compare ao5 instead of single times; leaderboard for wins or competitive ranking.

Acceptance ideas:
- Define a basic scoring model for room rounds.
- Display round wins/solve wins in the room UI.
- Consider session average / ao5 comparison modes.
- Keep this separate from permanent global rankings unless/until ranking is designed.