Fix undefined variable in p2p_chat.py show_conversations handler

- Change 'user.id' to 'sender.id' in line 205
- Error: NameError: name 'user' is not defined
- Issue occurred when calling /chat -> Мои диалоги callback

src/handlers/p2p_chat.py

@@ -204,7 +204,7 @@ async def show_conversations(callback: CallbackQuery):
             last_name=callback.from_user.last_name
         )
         
-        conversations = await P2PMessageService.get_recent_conversations(session, user.id, limit=10)
+        conversations = await P2PMessageService.get_recent_conversations(session, sender.id, limit=10)
     
     if not conversations:
         await callback.message.edit_text(