feat: add css-only accordion component submission

[Pratik-kr21]

Description

This PR introduces a new Accordion component submission to the submissions/examples/accordion-pr/ directory.

• Provides a clean, modern UI for FAQs and collapsible content panels.
• Completely JavaScript-free. It uses the hidden checkbox hack (:checked state) to manage the open/close interactivity.
• Utilizes CSS Grid (grid-template-rows: 0fr to 1fr) for a smooth, performant height transition that aligns with EaseMotion's fluid animation philosophy.

Submission Checklist

• Placed the feature inside the correct track directory (submissions/examples/)
• Included all required files (demo.html, style.css, README.md)
• Appended a unique identifier (-pr) to the feature directory name to prevent naming conflicts
• Verified that demo.html works directly in a browser without any external dependencies or build steps
• Focused this PR strictly on one component
• Kept a clean commit history using the Conventional Commits format

[SAPTARSHI-coder]

✅ Submission Validation Passed!

Great job! All required files are present and valid.

📁 Folder: submissions/examples/accordion-pr

Files found:

• ✅ demo.html
• ✅ style.css
• ✅ README.md

🚀 Next Steps:

• A maintainer will review your PR
• Respond to any feedback if requested
• Once approved, your contribution will be merged!

Thank you for contributing to EaseMotion CSS! 🎉

[SAPTARSHI-coder]

✅ Submission Validation Passed!

Great job! All required files are present and valid.

📁 Folder: submissions/examples/accordion-pr

Files found:

• ✅ demo.html
• ✅ style.css
• ✅ README.md

🚀 Next Steps:

• A maintainer will review your PR
• Respond to any feedback if requested
• Once approved, your contribution will be merged!

Thank you for contributing to EaseMotion CSS! 🎉