feat: add custom gameOver condition to GameOptions

- Add optional gameOver field to GameOptions
- Can be a boolean value or a function that receives scoreManager
- Function receives current score metrics to make dynamic decisions
- Enables flexible game-over conditions beyond just time limit
- Example: gameOver: (sm) => sm.efficiency > 150 for efficiency threshold
- Checked every frame during 'started' and 'has-key' states

src/types.ts

@@ -12,6 +12,7 @@ export type GameOptions = {
   rows: number;
   cols: number;
   timeLimit?: number;
+  gameOver?: boolean | ((scoreManager: ScoreManager) => boolean);
 };
 
 export type KeyLogEntry = { key: string; timestamp: number };