fix(realtime,ui): sync message deletes and channel delete/leave behavior

app/messages/service.py

@@ -206,6 +206,11 @@ async def delete_message(db: AsyncSession, *, message_id: int, user_id: int) ->
     membership = await chats_repository.get_chat_member(db, chat_id=message.chat_id, user_id=user_id)
     if not membership:
         raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="You are not a member of this chat")
+    if chat.type == ChatType.CHANNEL and not chat.is_saved:
+        raise HTTPException(
+            status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
+            detail="Channel messages can only be deleted for everyone",
+        )
     # Telegram-like default: delete only for current user.
     hidden = await repository.get_hidden_message(db, message_id=message.id, user_id=user_id)
     if not hidden: