Create a snake game

[feason]

Description

• This PR implements a classic Snake game using HTML5 Canvas and JavaScript.
• Summary of changes:
  • Adds index.html to set up the game's UI, including the canvas, score display, high score, controls, and a game over overlay.
  • Adds game.js which contains the complete game logic:
    • Snake movement, growth, and collision detection (walls and self).
    • Random food generation, ensuring it doesn't overlap with the snake.
    • Score tracking and high score persistence using local storage.
    • Dynamic game speed increase based on score.
    • Pause/resume functionality.
    • Rendering with modern visual effects for the snake, food, and background.
• Issues fixed: None. This PR fulfills a new feature request.

Screenshots/videos:

Checklist:

• I have read contributing wiki page
• I have performed a self-review of my own code
• My code follows the style guidelines
• My code passes tests

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[cursor]

Cursor Agent can help with this pull request. Just @cursor in comments and I'll start working on changes in this branch.
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