Allow admins to see true author of anonymous posts

[JoshuaNam]

Description

Admins/instructors can see the real author of anonymous posts, while students cannot.

Acceptance Criteria

• If isAnonymous is true and the viewer IS an admin/instructor, display the real username
• Next to the username, show a visual indicator (e.g., "(posted anonymously)" label or an eye-slash icon) so admins know the post is anonymous to others
• Admin can click the username to view the author's profile
• This applies to: post detail view, post listings, and category views

Community forum reference

No response