Clarify lack of support on archived course pages

### Describe the Issue

Archived courses (e.g. Back-End Development and APIs V8) show a note that the content "is not being updated," but this doesn't communicate that bug/support requests for these courses also aren't handled. Users still see the "Ask for help" button on individual challenge pages, which implies support is available - leading to confusion (see #65362).

### Expected behavior

The existing "not being updated" note on archived course landing pages should also make clear that no support is provided for bugs in this content. Additionally, the "Ask for help" button on individual challenge pages within archived courses should be hidden or replaced with a note pointing back to the archived-course notice.

### Screenshots

Start by locating the archived-course landing page notice and the challenge-page "Ask for help" entry point. Trace how archived-course status is identified, then verify that the landing-page notice explains the lack of bug support and that the challenge-page support control is hidden or points back to that notice.

Written by the indexing model from the issue text.