Thread extension-provided headers and cookies into Firelink media metadata loading so authenticated page fetches show the correct formats.
Include those auth inputs in both metadata and yt-dlp info-json cache keys to prevent cross-session collisions, and advance the Firefox extension submodule to the published media-fetch commit.
Normalize system proxy values from sysproxy, Windows registry, and environment fallbacks before handing them to download engines.
Apply the resolved proxy to direct metadata probes and yt-dlp media metadata requests so preview and final downloads use the same network path.
Enable reqwest SOCKS support and key media metadata caches by proxy/cookie inputs to avoid stale cross-proxy reuse.
NimBold