feat: Add sound effects support with terminal bells 🔔

Implements terminal bell-based sound effects throughout the rage-quit experience:

- Added new sound module with SoundPlayer and SoundEffect types
- New CLI flags: --sound and --bell-only
- Sound effects integrated into all phases:
  * Rage meter buildup (rapid bells)
  * Explosion phase (crescendo)
  * Fake error messages (error beeps)
  * Progress bars (success chimes)
  * Mic drop finale (dramatic sequence)

- Prepared infrastructure for future full audio support via optional 'audio' feature
- Updated README with sound documentation
- Added CHANGELOG.md to track changes

The implementation uses terminal bell characters (\x07) for maximum compatibility
across all terminals without requiring external dependencies. Full audio support
with actual sound files can be added later as an optional feature.

Closes the "Sound effects mode (terminal bell abuse)" item from Contributing section.
