feat : add liquid blob button

[kavin553]

PR Description

## Pull Request Description

Adds a button with a liquid blob fill animation that expands smoothly from the center on hover, built entirely with CSS keyframes. Closes #50555.

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## Type of Change

- [x] ✨ New animation / hover effect
- [ ] 🧩 New component
- [ ] 📝 Documentation improvement
- [ ] 🐛 Bug fix in an existing submission
- [ ] Other (describe below)

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## Submission Checklist

- [x] All changes are inside `submissions/` (`submissions/examples/liquid-button/`)
- [x] Includes `demo.html` — self-contained, opens in browser with no server
- [x] Includes `style.css` — raw CSS for the proposed feature
- [x] Includes `README.md` — what it does, how to use it, why it fits EaseMotion CSS
- [x] **No changes to `core/`**
- [x] **No changes to `components/`**
- [x] One feature per PR (no bundled unrelated changes)

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## Feature Description

**What does this add?**

A button whose fill animates outward from the center on hover like a liquid blob, using a wobbling `border-radius` keyframe animation for a soft, organic feel.

**How does a developer use it?**

```html
<button class="liquid-btn">Get Started</button>

[SAPTARSHI-coder]

✅ Submission Validation Passed!

Great job! All required files are present and valid.

📁 Folder: submissions/examples/animation-liquid-blob-button

Files found:

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

🚀 Next Steps:

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

Thank you for contributing to EaseMotion CSS! 🎉

[github-actions]

🎉 Congratulations on your PR merge, @kavin553! 🚀

Thank you so much for your valuable contribution to EaseMotion CSS! Your code is now merged into the main branch.

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[github-actions]

🎉 Pull Request Integrated!

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