Release v0.4.0 - HD Thumbnails, YouTube 2024+ Support, and yt-dlp Integration

Major Features:
- HD video thumbnails (hq720.jpg) with automatic fallback to lower qualities
- HD channel avatars (240x240 instead of 88x88)
- YouTube 2024+ lockupViewModel support for channel playlists
- youtubei/v1/browse API integration for channel playlist tabs
- yt-dlp integration for multi-language audio and subtitles

Bug Fixes:
- Fixed undefined `abort` import in playlist.py
- Fixed undefined functions in proto.py (encode_varint, bytes_to_hex, succinct_encode)
- Fixed missing `traceback` import in proto_debug.py
- Fixed blurry playlist thumbnails using default.jpg instead of HD versions
- Fixed channel playlists page using deprecated pbj=1 format

Improvements:
- Automatic thumbnail fallback system (hq720 → sddefault → hqdefault → mqdefault → default)
- JavaScript thumbnail_fallback() handler for 404 errors
- Better thumbnail quality across all pages (watch, channel, playlist, subscriptions)
- Consistent HD avatar display for all channel items
- Settings system automatically adds new settings without breaking user config

Files Modified:
- youtube/watch.py - HD thumbnails for related videos and playlist items
- youtube/channel.py - HD thumbnails for channel playlists, youtubei API integration
- youtube/playlist.py - HD thumbnails, fixed abort import
- youtube/util.py - HD thumbnail URLs, avatar HD upgrade, prefix_url improvements
- youtube/comments.py - HD video thumbnail
- youtube/subscriptions.py - HD thumbnails, fixed abort import
- youtube/yt_data_extract/common.py - lockupViewModel support, extract_lockup_view_model_info()
- youtube/yt_data_extract/everything_else.py - HD playlist thumbnails
- youtube/proto.py - Fixed undefined function references
- youtube/proto_debug.py - Added traceback import
- youtube/static/js/common.js - thumbnail_fallback() handler
- youtube/templates/*.html - Added onerror handlers for thumbnail fallback
- youtube/version.py - Bump to v0.4.0

Technical Details:
- All thumbnail URLs now use hq720.jpg (1280x720) when available
- Fallback handled client-side via JavaScript onerror handler
- Server-side avatar upgrade via regex in util.prefix_url()
- lockupViewModel parser extracts contentType, metadata, and first_video_id
- Channel playlist tabs now use youtubei/v1/browse instead of deprecated pbj=1
- Settings version system ensures backward compatibility

youtube/watch.py

@@ -628,7 +628,12 @@ def get_watch_page(video_id=None):
 
     # prefix urls, and other post-processing not handled by yt_data_extract
     for item in info['related_videos']:
-        item['thumbnail'] = "https://i.ytimg.com/vi/{}/hqdefault.jpg".format(item['id']) # set HQ relateds thumbnail videos
+        # For playlists, use first_video_id for thumbnail, not playlist id
+        if item.get('type') == 'playlist' and item.get('first_video_id'):
+            item['thumbnail'] = "https://i.ytimg.com/vi/{}/hq720.jpg".format(item['first_video_id'])
+        elif item.get('type') == 'video':
+            item['thumbnail'] = "https://i.ytimg.com/vi/{}/hq720.jpg".format(item['id'])
+        # For other types, keep existing thumbnail or skip
         util.prefix_urls(item)
         util.add_extra_html_info(item)
     for song in info['music_list']:
@@ -636,6 +641,9 @@ def get_watch_page(video_id=None):
     if info['playlist']:
         playlist_id = info['playlist']['id']
         for item in info['playlist']['items']:
+            # Set high quality thumbnail for playlist videos
+            if item.get('type') == 'video' and item.get('id'):
+                item['thumbnail'] = "https://i.ytimg.com/vi/{}/hq720.jpg".format(item['id'])
             util.prefix_urls(item)
             util.add_extra_html_info(item)
             if playlist_id:
@@ -692,12 +700,24 @@ def get_watch_page(video_id=None):
     audio_tracks = []
     try:
         from youtube import ytdlp_integration
+        logger.info(f'Extracting audio tracks for video: {video_id}')
         ytdlp_info = ytdlp_integration.extract_video_info_ytdlp(video_id)
         audio_tracks = ytdlp_info.get('audio_tracks', [])
+
         if audio_tracks:
-            logger.info(f'Found {len(audio_tracks)} audio tracks for video {video_id}')
+            logger.info(f'✓ Found {len(audio_tracks)} audio tracks:')
+            for i, track in enumerate(audio_tracks[:10], 1):  # Log first 10
+                logger.info(f'  [{i}] {track["language_name"]} ({track["language"]}) - '
+                          f'bitrate: {track.get("audio_bitrate", "N/A")}k, '
+                          f'codec: {track.get("acodec", "N/A")}, '
+                          f'format_id: {track.get("format_id", "N/A")}')
+            if len(audio_tracks) > 10:
+                logger.info(f'  ... and {len(audio_tracks) - 10} more')
+        else:
+            logger.warning(f'No audio tracks found for video {video_id}')
+
     except Exception as e:
-        logger.warning(f'Failed to extract audio tracks: {e}')
+        logger.error(f'Failed to extract audio tracks: {e}', exc_info=True)
         audio_tracks = []
 
     pair_quality = yt_data_extract.deep_get(pair_sources, pair_idx, 'quality')
@@ -834,9 +854,17 @@ def get_watch_page(video_id=None):
 
 @yt_app.route('/api/<path:dummy>')
 def get_captions(dummy):
-    result = util.fetch_url('https://www.youtube.com' + request.full_path)
-    result = result.replace(b"align:start position:0%", b"")
-    return result
+    try:
+        result = util.fetch_url('https://www.youtube.com' + request.full_path)
+        result = result.replace(b"align:start position:0%", b"")
+        return result
+    except util.FetchError as e:
+        # Return empty captions gracefully instead of error page
+        logger.warning(f'Failed to fetch captions: {e}')
+        return flask.Response(b'WEBVTT\n\n', mimetype='text/vtt', status=200)
+    except Exception as e:
+        logger.error(f'Unexpected error fetching captions: {e}')
+        return flask.Response(b'WEBVTT\n\n', mimetype='text/vtt', status=200)
 
 
 times_reg = re.compile(r'^\d\d:\d\d:\d\d\.\d\d\d --> \d\d:\d\d:\d\d\.\d\d\d.*$')