feat: added shapes choices in main menu

[Satvik-Singh192]

Description

Added a simple and beginner-friendly Player Shape Selection feature.
A new button was added in the Main Menu that lets the player choose between different shapes (Cube, Sphere, Capsule).
The selected shape is stored using a lightweight static variable and applied when every level loads.
This implementation is intentionally minimal, avoids complex managers, and is easy to copy into additional levels.

Semver Changes

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

Issues

Closes #82 (Add “Choice of Player Shapes”)

Checklist

• I have read the Contributing Guidelines.

[Satvik-Singh192]

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

[Just-Here-TO-Code]

Good work, merging your PR.