feat: centralize common English words for language detection

Move COMMON_ENGLISH_WORDS set from youtube_transcript_downloader.py to language_codes.py as a shared constant. This improves code organization and reusability, allowing other modules to reference the same word list for English language detection.

youtube_transcript_downloader.py

@@ -19,12 +19,14 @@ def extract_video_id(url):
     patterns = [
         r'(?:v=|\/)([0-9A-Za-z_-]{11}).*',
         r'youtu\.be\/([0-9A-Za-z_-]{11})',
+        r'([0-9A-Za-z_-]{11})'
     ]
     
     for pattern in patterns:
         match = re.search(pattern, url)
         if match:
             return match.group(1)
+    
     return None