Fixes the "Filter Forge" tab not appearing on Mobalytics build pages viewed under a creator's
profile (URLs shaped like mobalytics.gg/diablo-4/profile/<creator>/builds/<slug>, rather than
mobalytics.gg/diablo-4/builds/<slug>). Both URL shapes are now recognized, in the extension's
panel and its in-page button alike.

Confirmed in both Firefox and Chrome (tested via Edge, which shares Chrome's extension engine).

No changes to filter generation, strictness levels, or the other three supported sites.

Fixes the extension not working at all in Firefox — the panel would open but stay blank on every
supported site. (Firefox restricts a browser API for extension pages loaded inside another site's
page; lookups now go through the extension's background page instead, which isn't affected.)

Fixes the "Filter Forge" tab occasionally disappearing after a page finished loading, on sites whose
own scripts rebuild parts of the page after the initial load.

No changes to filter generation, strictness levels, or supported sites.