Enhance CAPTCHA Validator: Mobile Responsive, Modular JS, and Accessibility Improvements

[AbhinashRao]

🛠️ Summary

This PR includes multiple improvements to the CAPTCHA Validator project to enhance usability, maintainability, and accessibility. These changes make the project cleaner, responsive, and more professional for end-users and recruiters alike.

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✅ What's Changed

• ♻️ Refactored script.js to modularize CAPTCHA generation logic.
• 🧪 Added keyboard event (Enter key) for user convenience.
• 🔁 Implemented functional "Refresh CAPTCHA" button.
• 📱 Made the layout responsive for mobile and smaller screens via media queries in styles.css.
• 🎨 Improved layout spacing and padding for better visual structure.
• ♿ Enhanced accessibility and semantic structure for screen readers.
• 📘 Added a professional README.md with features, demo, and usage instructions.

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💡 Motivation

These changes are intended to:

• Improve first impressions for users accessing on different devices.
• Follow modern JS practices with clean functions.
• Make the project suitable for production or as a strong candidate for open-source contribution.

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✅ Checklist

• [x] Code runs successfully in modern browsers.
• [x] UI is mobile-friendly and responsive.
• [x] CAPTCHA refresh and validation works as expected.
• [x] Files and folders are properly structured and documented.