Strip '- Topic' suffix from YouTube auto-generated channel names (#231)

YouTube's auto-generated artist channels use the format "Artist - Topic"
as the channel name. This suffix was not being stripped during playlist
parsing, causing metadata discovery to fail (e.g., searching for
"Koven - Topic" instead of "Koven" on iTunes/Deezer).

Fixed in all three places where YouTube artist names are cleaned:
- web_server.py clean_youtube_artist() — playlist parsing
- ui/pages/sync.py clean_youtube_artist() — UI-side parsing
- core/youtube_client.py — search result fallback artist extraction

core/youtube_client.py

@@ -508,6 +508,9 @@ class YouTubeClient:
         # Fallback: use uploader/channel as artist
         if not artist:
             artist = entry.get('uploader', entry.get('channel', 'Unknown Artist'))
+            # Strip YouTube auto-generated "- Topic" suffix from channel names
+            if artist and re.search(r'\s*-\s*Topic\s*$', artist, re.IGNORECASE):
+                artist = re.sub(r'\s*-\s*Topic\s*$', '', artist, flags=re.IGNORECASE).strip()
 
         # Extract file size (estimate from format)
         file_size = 0

ui/pages/sync.py

@@ -289,6 +289,7 @@ def clean_youtube_artist(artist_string):
     
     # Remove common YouTube channel suffixes
     channel_suffixes = [
+        r'\s*-\s*Topic\s*$',       # YouTube auto-generated "Topic" channels
         r'\s*VEVO\s*$',
         r'\s*Music\s*$',
         r'\s*Official\s*$',

web_server.py

@@ -14872,6 +14872,7 @@ def clean_youtube_artist(artist_string):
     
     # Remove common YouTube channel suffixes
     channel_suffixes = [
+        r'\s*-\s*Topic\s*$',       # YouTube auto-generated "Topic" channels (e.g. "Koven - Topic")
         r'\s*VEVO\s*$',
         r'\s*Music\s*$',
         r'\s*Official\s*$',