feat: cleanup Carbon override stylesheet

[MCatherine1994]

Following the documentation in this issue, I cleaned up the existing Carbon override stylesheet, regrouped the style changes by component, and added comments for each section. There was no style change, just cleanup and refactoring.

[Copilot]

Pull Request Overview

This PR refactors the Carbon override stylesheet to improve organization and maintainability. The cleanup includes grouping styles by component, adding descriptive comments for each section, and reorganizing the code structure without making any functional style changes.

• Regrouped CSS overrides by Carbon component type with clear section headers
• Added detailed comments explaining the styling changes for each component
• Updated font file paths to use newer BC Sans font variants with light weight support

Reviewed Changes

Copilot reviewed 3 out of 16 changed files in this pull request and generated 2 comments.

File	Description
style-sheets/overrides.scss	Complete reorganization of CSS overrides with component-based grouping and comprehensive commenting
design-tokens/type-family.scss	Updated font file paths and added light font weight support
README.md	Added new React usage documentation with code examples

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}