Get the latest tweets that mention the authenticated user (the notifications timeline). Returns up to 20 tweets per page, most recent first, with pagination support. Query params: auth_token (string, required) - Twitter auth_token cookie; ct0 (string, required) - Twitter ct0 cookie; type (string, optional) - notifications timeline to read: All (default), Priority, or Mentions; next_token (string, optional) - pagination cursor. Returns X v2 API-compatible JSON.