feat(stream): transcode debrid sources to HLS from a URL (hueco #2/2b)

Non-browser-native debrid content (mkv/HEVC/…) can now stream: ffmpeg reads
the debrid HTTPS link directly (-i <url>) and transcodes to HLS, instead of
2a's raw direct-play which only works for mp4/m4v.

- HLSSessionConfig gains SourceURL + CacheID; sourceRef() feeds ffprobe,
  ffmpeg -i, and subtitle extraction from one place. HTTP-resilience flags
  (-reconnect*, -rw_timeout) are added only for a URL source; a seek-restart
  re-opens the URL with a Range request (-ss before -i = input seek).
- Segment cache keys by CacheID (the torrent info_hash) for URL sessions so
  re-plays hit cache despite the debrid URL changing each resolution
  (KeyForID, no filepath.Abs).
- OnStreamSession: the 2a direct-play branch is now gated on PlayMethod != "hls";
  a new branch handles DirectURL + PlayMethod=="hls" → HLS-from-URL. The
  local-file and both debrid HLS paths share a startHLSPlayback helper.
- ExtractMediaInfo no longer masks a URL probe failure as "file not found"
  (surfaces ffprobe's real stderr, e.g. "Protocol not found" on a TLS-less
  ffmpeg build).
- Bump 0.11.0 -> 0.12.0 as the HLS-from-URL floor the web gates on.

Validated e2e against real AllDebrid: a cached HEVC x265 mkv transcodes
(h264_nvenc) from the debrid URL and plays 1080p in Chrome via hls.js,
subtitles extracted from the remote mkv.

internal/library/mediainfo/ffprobe.go

@@ -67,8 +67,14 @@ func ExtractMediaInfo(ctx context.Context, ffprobePath, filePath string) (*Media
 
 	output, err := cmd.Output()
 	if err != nil {
-		if _, statErr := os.Stat(filePath); statErr != nil {
-			return nil, fmt.Errorf("ffprobe: file not found: %s", filePath)
+		// A remote URL (debrid HLS-from-URL, hueco #2/2b) has no local file to
+		// stat — surface ffprobe's own stderr (e.g. "Protocol not found" when the
+		// ffmpeg build lacks TLS, or an HTTP error) instead of a misleading
+		// "file not found". Only treat a genuine local path as possibly-missing.
+		if !strings.Contains(filePath, "://") {
+			if _, statErr := os.Stat(filePath); statErr != nil {
+				return nil, fmt.Errorf("ffprobe: file not found: %s", filePath)
+			}
 		}
 		return nil, fmt.Errorf("ffprobe failed (file=%s): %s", filePath, stderr.String())
 	}