feat: added a click soundeffect to all buttons in main menu

[Satvik-Singh192]

Description

Added button click sound effects to the Main Menu.
Implemented a lightweight delayed-scene-loading system in MainMenu.cs so UI click audio can play fully before switching scenes.
Updated Play, Shop, and Quit buttons to use PlayGame(), GoToShop(), and QuitGame() methods correctly, ensuring all buttons now produce consistent audio feedback without affecting existing gameplay logic.

Semver Changes

• Patch (bug fix, no new features)
• Minor (new features, no breaking changes)
• Major (breaking changes)

Issues

Closes #98

Checklist

• I have read the Contributing Guidelines.

[Satvik-Singh192]

@Just-Here-TO-Code please review my pull request

[Just-Here-TO-Code]

Nicely done, thanks for the contribution, merging your PR.