fix: support YouTube 2024+ data formats for playlists, podcasts and channels

- Add PODCAST content type support in lockupViewModel extraction
- Extract thumbnails and episode count from thumbnail overlay badges
- Migrate playlist page fetching from pbj=1 to innertube API (youtubei/v1/browse)
- Support new pageHeaderRenderer format in playlist metadata extraction
- Fix subscriber count extraction when YouTube returns handle instead of count
- Hide "None subscribers" in template when data is unavailable

youtube/templates/common_elements.html

@@ -58,7 +58,9 @@
 
                 <div class="stats {{'horizontal-stats' if horizontal else 'vertical-stats'}}">
                     {% if info['type'] == 'channel' %}
-                        <div>{{ info['approx_subscriber_count'] }} subscribers</div>
+                        {% if info.get('approx_subscriber_count') %}
+                            <div>{{ info['approx_subscriber_count'] }} subscribers</div>
+                        {% endif %}
                         <div>{{ info['video_count']|commatize }} videos</div>
                     {% else %}
                         {% if info.get('time_published') %}