Web UI on non-https doesn't respond sensibly

When the web UI is only enabled over http**s**, trying to access it over http doesn't send a sensible response. I get some binary gibberish on one browser, and a browser error message on another.

It would make more sense to redirect http to https.

Start by locating the web UI's HTTP and HTTPS listener or request-handling entry points and inspect how HTTP-only access currently behaves when HTTPS is enabled. Confirm the desired behavior from the issue: HTTP requests should redirect to HTTPS rather than return browser errors or binary data, and verify the behavior with the relevant web UI checks.

Written by the indexing model from the issue text.