feat: Complete Mail Composer with EmailJS integration

- Rich email composer with formatting tools (bold, italic, underline, links)
- Multi-recipient support (To, CC, BCC fields)
- File attachments with drag & drop support
- Priority levels and email validation
- Draft management with auto-save and cloud sync
- Real email sending via EmailJS integration
- Responsive design for mobile and desktop
- Comprehensive error handling and fallback modes
- Complete documentation and setup guides
- Firebase integration ready for advanced features

Features:
✅ Real email sending (EmailJS)
✅ Rich text editor
✅ File attachments
✅ Draft management
✅ Form validation
✅ Responsive UI
✅ Error handling
✅ Documentation

public/vite.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+  <path d="M4 4h16c1.1 0 2 .9 2 2v12c0 1.1-.9 2-2 2H4c-1.1 0-2-.9-2-2V6c0-1.1.9-2 2-2z"/>
+  <polyline points="22,6 12,13 2,6"/>
+</svg>