feat: yt-dlp prefers H.264, falls back to built-in, no pipe hang (v1.0.0.13)

- Format string prefers avc1 video + m4a audio, then any codec. The RTX 2070
  host can hardware-transcode H.264 but not AV1.
- Pass Jellyfin's ffmpeg via --ffmpeg-location instead of relying on PATH.
- If yt-dlp fails, retry with the built-in YoutubeExplode downloader.
- Read stdout/stderr while yt-dlp runs (and add --no-progress); before,
  stdout was never read, so a full pipe buffer could block yt-dlp forever.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

build.yaml

@@ -1,5 +1,5 @@
 ---
-version: 1.0.0.12
+version: 1.0.0.13
 name: CinemaTrailers4Jellyfins
 guid: b581493e-1046-40ed-b6dc-cb8027624984
 description: >
@@ -12,12 +12,12 @@ category: General
 owner: 514mart
 targetAbi: 10.11.0.0
 changelog:
-  - Anime trailers now only play before anime. Western animation (Pixar,
-    Disney, ...) is no longer blocked and follows the normal genre filter
-    again. A trailer counts as anime when TMDB tags it "anime" or "based on
-    manga", or it is animation in Japanese, Chinese or Korean; it is marked
-    with a ct4j-anime tag in its NFO at download time. Your anime is
-    recognised by the "Anime" genre or the same TMDB keywords
+  - yt-dlp now prefers H.264 + AAC (plays or hardware-transcodes on every
+    client; VP9/AV1 often needed a CPU transcode) and uses Jellyfin's own
+    ffmpeg for the merge
+  - If yt-dlp fails, the built-in downloader is tried instead
+  - Fix a possible hang: yt-dlp's output is now read while it runs, so a
+    full output buffer can no longer block it
 
 dotnetProjects:
   - name: Jellyfin.Plugin.CinemaTrailers4Jellyfins