Localhost not supported

[KingMob]

Describe the bug
It can be difficult to get a decent logo in the right size, so frequently I download a file, and edit or upscale it locally. Since file:/// URLs aren't valid, this time around, I figured I'd run a local web server (python3 -m http.server) from the file's directory for the logo URL.

When I gave FTWA a valid localhost URL (http://localhost:8000/microconf%20logo%201024.png), FTWA complained. I checked in the browser, and the URL worked just fine there. When I gave FTWA a 127.0.0.1-based URL, it worked. When I gave it one of the localhost aliases from my /etc/hosts file, e.g., example.localhost, it worked. But on plain localhost, FTWA fails for some reason.

To Reproduce
Steps to reproduce the behavior:

1. Create a valid logo png file
2. cd to the directory
3. Start a web server, e.g. python3 -m http.server
4. Create a http://localhost:8000/path-to-file.png URL
5. Paste the URL into the logo URL entry
6. FTWA will say "Invalid logo URL"

Expected behavior
localhost should be treated like any other URL.

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: macOS 15.2
• Browser Firefox Develoepr Edition
• Version 134.0b10