Fix Snake game restart functionality after game over

[siri-004]

📝 Description

Fixed broken restart functionality in the Snake Game after reaching the GAME OVER state.

✅ Changes Made

• Added a centralized restartGame() function
• Removed page reload behavior from restart button
• Fixed overlay restart button not restarting gameplay
• Properly reset snake position, score, direction, and food
• Ensured both restart buttons restart the game inside the modal

🎯 Result

Both restart buttons now correctly reset and restart the game without closing the modal or freezing gameplay.

🔗 Linked Issue

Closes #500

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📋 Contribution Checklist

• My code strictly adheres to the project guidelines (Standard library only, procedural code, clean spacing).
• I have verified that my files are placed in the correct directory.
• I have tested my changes thoroughly on my local machine.
• I have included interactive emojis and clean console/UI outputs.
• GSSoC 2026: I have been formally assigned to this issue and noted it above.

[vercel]

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[github-actions]

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