refactor(game): extract constants from InfiniteRunner to improve code organization

- Created utils/constants/games/infinite-runner.ts with all game constants
- Moved physics, speed configs, game costs, themes, audio config, scoring, timing, and quiz questions to constants file
- Refactored InfiniteRunner.tsx to use imported constants instead of hardcoded values
- Fixed TypeScript type narrowing issues with obstacle type checks
- Improved code maintainability and readability
- All constants now centralized in single source of truth

Author: josegomez-dev