fix: send account deletion notification before deleting user row

When deleting a user via CLI (`vikunja user delete <id> -n`), the user
row was deleted first, then `notifications.Notify` was called. But
`Notify` calls `User.ShouldNotify()` which queries the database to check
the user's status — and since the row was already deleted within the same
transaction, it returned `ErrUserDoesNotExist`.

Move the notification call before the `DELETE` so the user row still
exists when `ShouldNotify` checks it.

Closes go-vikunja/vikunja#2335

pkg/models/user_delete.go

@@ -169,14 +169,17 @@ func DeleteUser(s *xorm.Session, u *user.User) (err error) {
 		}
 	}
 
-	_, err = s.Where("id = ?", u.ID).Delete(&user.User{})
+	// Notify before deleting the user row, because ShouldNotify will try to
+	// look up the user and fail if the row is already gone.
+	err = notifications.Notify(u, &user.AccountDeletedNotification{
+		User: u,
+	}, s)
 	if err != nil {
 		return err
 	}
 
-	return notifications.Notify(u, &user.AccountDeletedNotification{
-		User: u,
-	}, s)
+	_, err = s.Where("id = ?", u.ID).Delete(&user.User{})
+	return err
 }
 
 func ensureProjectAdminUser(s *xorm.Session, l *Project) (hadUsers bool, err error) {