Masquerade bar mounts for anonymous users and shows partial shell on failed loads #265

Description

MasqueradeBar renders a partial empty shell with a "Unable to load masquerade options." alert whenever its query fails for any reason other than an explicit 403. This is the common case for users who are not logged in: the LMS responds with a 302 redirect to /login rather than a 403. The code treats the resulting HTML response as a generic "unreachable" failure and shows the broken-looking alert instead of hiding the bar.

The expected behavior is that the bar renders only when the query succeeds with success: true, and never mounts for anonymous users.