Email Transfer System - Complete Fix & Enhancement

1. Double Transfer Protection

• Added: Loading state and duplicate transfer detection
• Result: Users can't accidentally transfer the same email multiple times

2. Email Transfer Notifications

• Added: Email notification sent to recipients when they receive a transferred KadeEmail

3. Transferred Emails Page

• Updated: Shows both emails transferred by user and emails received by user
• Added: "Type" column (Transferred/Received) and "Transferred On" date column

All transfer functionality now works smoothly with proper validation and user feedback!