Add room scoring and win/loss counters

[coder13]

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.