feat: Enhance User model with URL validation and documentation

[dheeraj00733]

• Add JSDoc documentation for better code readability
• Implement URL validation for social media links
• Add bio length validation (max 500 chars)
• Add skills limit validation (max 20 skills)
• Add descriptive error messages for validation failures

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• ✅ My issue is assigned to me, and I have not taken up another task simultaneously.
• 🔁 I have pulled the latest changes from the main branch.
• 🧪 My code is tested and does not break existing functionality.
• 📚 I have added/updated documentation wherever necessary.
• 🧹 My code follows the project’s coding standards.
• ✍️ My commits are clear and meaningful.
• 🧾 I have linked the issue this PR addresses with Closes #<issue_number>.

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📌 Related Issue

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🧠 Description

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✅ Type of Change

• 🐞 Bug fix
• 💡 Feature
• 🧹 Code cleanup/refactor
• 🧪 Test cases
• 📚 Docs update

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📝 Additional Notes (Optional)

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[vercel]

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[github-actions]

🙌 Thanks @dheeraj00733 for raising this PR!
Our team will review it soon ⏳ — meanwhile, please make sure your PR follows our contributing guidelines 👉 Contributing Guidelines 🎉