Add database schema for best-of-3 scoring

[JvmName]

Move from continuous riding time to discrete point-based scoring with best-of-3 rounds.

Note: I don't feel strongly about how we track each round winner, this is just a suggestion on how to do it.

Migrations needed:

1. Update matches table:

+ round_1_winner_id (UUID, nullable)
+ round_2_winner_id (UUID, nullable)  
+ round_3_winner_id (UUID, nullable)
+ match_winner_id (UUID, nullable)
+ status (ENUM: 'pending', 'in_progress', 'completed')
- red_score
- blue_score

2. Update rounds table:

+ round_index (INTEGER, NOT NULL)
+ duration_seconds (INTEGER, NOT NULL)
+ point_threshold (INTEGER, NOT NULL)
+ red_points (INTEGER, DEFAULT 0)
+ blue_points (INTEGER, DEFAULT 0)
+ winner_id (UUID, nullable)
+ end_method (ENUM: 'submission', 'stoppage', 'techfall', 'points', null)
+ started_at (DATE)

No changes needed to riding_time_votes table.