feat(media): support extension media fetch

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.

src/utils/mediaMetadata.ts

@@ -6,13 +6,23 @@ type FetchMediaMetadataArgs = {
   cookieBrowser: string | null;
   username: string | null;
   password: string | null;
+  headers: string | null;
+  cookies: string | null;
   proxy: string | null;
 };
 
 const inFlightMediaMetadata = new Map<string, Promise<MediaMetadata>>();
 
 const metadataKey = (args: FetchMediaMetadataArgs) =>
-  JSON.stringify([args.url, args.cookieBrowser, args.username, args.password, args.proxy]);
+  JSON.stringify([
+    args.url,
+    args.cookieBrowser,
+    args.username,
+    args.password,
+    args.headers,
+    args.cookies,
+    args.proxy
+  ]);
 
 export const fetchMediaMetadataDeduped = (args: FetchMediaMetadataArgs): Promise<MediaMetadata> => {
   const key = metadataKey(args);