[Enhancement] Enhance Visual Feedback & Add Basic Customizations

### Problem:

The current Pong game is great, but adding more immediate visual feedback for hits/scores and basic customization options would greatly enhance the player experience. Without these, the game feels less "modern" and personalized.

### Proposed Solution:

Implement frontend changes to provide better visual cues and player choices:

* **Visual Feedback:** Add subtle effects (e.g., quick flash) when the ball hits a paddle or when a score occurs.
* **Customization:** Introduce simple volume sliders for audio and an option for players to change their paddle color.

### Why this is important:

These small additions significantly improve gameplay immersion and user personalization, directly contributing to the "modern touches" goal. This is a visible frontend improvement perfect for contribution.

I'm ready to tackle this using HTML, CSS, and JavaScript.