perf(media): optimize yt-dlp extraction speed and fix proxy propagation

- Add '--extractor-args youtube:player_client=ios,web' to bypass heavy JS challenge solving
- Add '--compat-options no-youtube-unavailable-videos' to skip blocked videos
- Fix missing proxy configuration in MediaExtractionEngine that caused timeouts
- Add '--live-from-start' for yt-dlp to handle live streams correctly

Sources/Firelink/AddDownloadsView.swift

@@ -603,7 +603,8 @@ struct AddDownloadsView: View {
                                     for: item.url,
                                     cookieSource: settings.mediaCookieSource,
                                     credentials: metadataCredentials(for: item.url),
-                                    transferOptions: transferOptions
+                                    transferOptions: transferOptions,
+                                    proxyConfiguration: settings.downloadProxyConfiguration
                                 )
                                 fetchedItem.mediaMetadata = metadata
                                 fetchedItem.mediaOptions = options

Sources/Firelink/MediaDownloadEngine.swift

@@ -45,6 +45,9 @@ final class MediaDownloadEngine: @unchecked Sendable {
             "--newline",
             "--ffmpeg-location", ffmpegURL.path,
             "--force-ipv4",
+            "--live-from-start",
+            "--extractor-args", "youtube:player_client=ios,web",
+            "--compat-options", "no-youtube-unavailable-videos",
             "-o", item.destinationPath
         ]
 

Sources/Firelink/MediaExtractionEngine.swift

@@ -69,7 +69,8 @@ enum MediaExtractionEngine {
         for url: URL,
         cookieSource: BrowserCookieSource,
         credentials: DownloadCredentials?,
-        transferOptions: DownloadTransferOptions
+        transferOptions: DownloadTransferOptions,
+        proxyConfiguration: DownloadProxyConfiguration
     ) async throws -> (MediaMetadata, [CleanFormatOption]) {
         guard let ytDlpURL = await MediaEngineManager.shared.binaryPath(for: .ytDlp),
               FileManager.default.isExecutableFile(atPath: ytDlpURL.path) else {
@@ -77,7 +78,20 @@ enum MediaExtractionEngine {
         }
         let ytDlpPath = ytDlpURL.path
 
-        var args = ["-J", "--no-warnings", "--ignore-no-formats-error", "--no-playlist", "--force-ipv4"]
+        var args = [
+            "-J", 
+            "--no-warnings", 
+            "--ignore-no-formats-error", 
+            "--no-playlist", 
+            "--force-ipv4",
+            "--extractor-args", "youtube:player_client=ios,web",
+            "--compat-options", "no-youtube-unavailable-videos"
+        ]
+
+        if let proxyURI = proxyConfiguration.customProxyURI, proxyConfiguration.mode == .custom {
+            args.append(contentsOf: ["--proxy", proxyURI])
+        }
+
         appendCommonArguments(to: &args, cookieSource: cookieSource, credentials: credentials, transferOptions: transferOptions)
         args.append(url.absoluteString)