Viewport selection vertex and face picking

[juanchuletas]

Pull Request Template

Description

This PR starts the FunGT feature that allows to create models from scratch.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Refactor (code change that neither fixes a bug nor adds a feature)
• Documentation (changes to docs only)
• Performance (improves performance)

Changes Made

Technical Details

Testing

• Tested locally
• Visual comparison before/after
• Performance benchmarked
• Edge cases verified

Screenshots / Results

Before	After

Performance Impact

• Render time before:
• Render time after:
• Memory usage:

Related Issues

Closes #

Checklist

• Code compiles without warnings
• Code follows project style guidelines
• Self-reviewed my own code
• Commented hard-to-understand areas
• No unnecessary debug code left behind

Notes for Reviewers