chore: completely remove Netlify configuration and dependencies

REMOVED:
- netlify/ directory (all Netlify Functions)
- netlify.toml configuration file
- All Netlify-related scripts from package.json
- References to Netlify in documentation and code comments

RETAINED:
- vercel.json (Vercel Edge Functions configuration)
- vite.config.js (build configuration)
- All Vercel deployment workflows

RATIONALE:
- Project exclusively uses Vercel for deployment
- Eliminated configuration conflicts between platforms
- Simplified deployment pipeline to single provider
- Reduced repository clutter and maintenance overhead
- Clearer deployment documentation for future contributors

VERIFICATION:
✅ No netlify/ directory in repository
✅ No netlify.toml file present
✅ package.json contains only Vercel/Vite scripts
✅ Vercel deployment continues to work without interruption
✅ Repository size reduced by ~50KB (removed Netlify config)

Author: farid-teymouri