remove yt-dlp, fix captions PO Token issue, fix 429 retry logic

- Remove yt-dlp entirely (modules, routes, settings, dependency)
  Was blocking page loads by running synchronously in gevent
- Fix captions: use Android client caption URLs (no PO Token needed)
  instead of web timedtext URLs that YouTube now blocks
- Fix 429 retry: fail immediately without Tor (same IP = pointless retry)
  Was causing ~27s delays with exponential backoff
- Accept ytdlp_enabled as legacy setting to avoid warning on startup

youtube/templates/watch.html

@@ -86,15 +86,6 @@
                         {% endfor %}
                     </select>
 
-                    {% if audio_tracks and audio_tracks|length > 1 %}
-                    <select id="audio-language-select" autocomplete="off" title="Audio language">
-                        {% for track in audio_tracks %}
-                            <option value="{{ track.get('track_id', track['language']) }}" {{ 'selected' if loop.index0 == 0 else '' }}>
-                                🔊 {{ track['language_name'] }}{% if track.get('is_default') %} (Default){% endif %}
-                            </option>
-                        {% endfor %}
-                    </select>
-                    {% endif %}
                 {% endif %}
             </div>
             <input class="v-checkbox" name="video_info_list" value="{{ video_info }}" form="playlist-edit" type="checkbox">
@@ -257,37 +248,6 @@
      // @license-end
     </script>
 
-    <!-- Audio language selector handler -->
-    <script>
-     // @license magnet:?xt=urn:btih:0b31508aeb0634b347b8270c7bee4d411b5d4109&dn=agpl-3.0.txt AGPL-v3-or-Later
-     (function() {
-         'use strict';
-         const audioSelect = document.getElementById('audio-language-select');
-         const qualitySelect = document.getElementById('quality-select');
-
-         if (audioSelect && qualitySelect) {
-             audioSelect.addEventListener('change', function() {
-                 const selectedAudio = this.value;
-                 const selectedQuality = qualitySelect.value;
-
-                 // Parse current quality selection
-                 let qualityData;
-                 try {
-                     qualityData = JSON.parse(selectedQuality);
-                 } catch(e) {
-                     return;
-                 }
-
-                 // Reload video with new audio language
-                 const currentUrl = new URL(window.location.href);
-                 currentUrl.searchParams.set('audio_lang', selectedAudio);
-                 window.location.href = currentUrl.toString();
-             });
-         }
-     }());
-     // @license-end
-    </script>
-
     <script src="/youtube.com/static/js/common.js"></script>
     <script src="/youtube.com/static/js/transcript-table.js"></script>
     {% if settings.use_video_player == 2 %}