- Remove frozen Message attribute assignment in back_to_menu handler
- Reconstruct chat menu properly instead of modifying frozen Message
- Add format_sender_name() function for consistent sender display
- Show user card number for admins in P2P dialogs
- Improve display of sender info with emoji indicators (🔵)
- Show card number in conversations list if available
Fixes: ValidationError: Instance is frozen on p2p:back_to_menu callback