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/yt_data_extract/watch_extraction.py

@@ -628,6 +628,7 @@ def extract_watch_info(polymer_json):
     info['manual_caption_languages'] = []
     info['_manual_caption_language_names'] = {}     # language name written in that language, needed in some cases to create the url
     info['translation_languages'] = []
+    info['_caption_track_urls'] = {}  # lang_code -> full baseUrl from player response
     captions_info = player_response.get('captions', {})
     info['_captions_base_url'] = normalize_url(deep_get(captions_info, 'playerCaptionsRenderer', 'baseUrl'))
     # Sometimes the above playerCaptionsRender is randomly missing
@@ -658,6 +659,10 @@ def extract_watch_info(polymer_json):
         else:
             info['manual_caption_languages'].append(lang_code)
         base_url = caption_track.get('baseUrl', '')
+        # Store the full URL from the player response (includes valid tokens)
+        if base_url:
+            normalized = normalize_url(base_url) if base_url.startswith('/') or not base_url.startswith('http') else base_url
+            info['_caption_track_urls'][lang_code + ('_asr' if caption_track.get('kind') == 'asr' else '')] = normalized
         lang_name = deep_get(urllib.parse.parse_qs(urllib.parse.urlparse(base_url).query), 'name', 0)
         if lang_name:
             info['_manual_caption_language_names'][lang_code] = lang_name
@@ -825,6 +830,21 @@ def captions_available(info):
 
 def get_caption_url(info, language, format, automatic=False, translation_language=None):
     '''Gets the url for captions with the given language and format. If automatic is True, get the automatic captions for that language. If translation_language is given, translate the captions from `language` to `translation_language`. If automatic is true and translation_language is given, the automatic captions will be translated.'''
+    # Try to use the direct URL from the player response first (has valid tokens)
+    track_key = language + ('_asr' if automatic else '')
+    direct_url = info.get('_caption_track_urls', {}).get(track_key)
+    if direct_url:
+        url = direct_url
+        # Override format
+        if '&fmt=' in url:
+            url = re.sub(r'&fmt=[^&]*', '&fmt=' + format, url)
+        else:
+            url += '&fmt=' + format
+        if translation_language:
+            url += '&tlang=' + translation_language
+        return url
+
+    # Fallback to base_url construction
     url = info['_captions_base_url']
     if not url:
         return None