{Feature}: Add Export Options (PNG, JPEG, WebP) And Download Quality Slider

[JwelSrivastava]

🔧 Description
This PR #138
adds export functionality to the Meme Generator, allowing users to:

• Download memes in multiple formats: PNG, JPEG, WebP
• Adjust download quality for JPEG/WebP using a slider
• Minor frontend improvements for a cleaner UI

🧩 Changes Made

• Export dropdown with file type selection
• Quality slider with dynamic preview
• Updated download logic for multiple formats

💡 How to Test

1. Create a meme
2. Choose format from dropdown
3. Adjust quality slider
4. Click "Download" — image should save correctly

🏷️ Notes

• Compatible with modern browsers
• Tested locally with different formats and qualities
• Hacktoberfest contribution 🎃

✅ Checklist

• Feature implemented
• UI tested locally
• No breaking changes
• Ready for review

🌸 Hacktoberfest 2025
Contribution made as part of Hacktoberfest 2025 — happy to support open-source!