Fix Jellyfin playlist track fetch truncating at default API limit

get_playlist_tracks() had no Limit or StartIndex params, so Jellyfin
defaulted to ~100 items per response. This caused the Server Playlists
comparison to show most tracks as missing even though they were present.

Now paginates in batches of 1000 until a partial batch signals the last page.

core/jellyfin_client.py

@@ -1472,22 +1472,33 @@ class JellyfinClient:
             return []
 
         try:
-            params = {
-                'ParentId': playlist_id,
-                'IncludeItemTypes': 'Audio',
-                'Recursive': True,
-                'Fields': 'AlbumId,ArtistItems,Path,MediaSources',
-                'SortBy': 'SortName',
-                'SortOrder': 'Ascending'
-            }
-            
-            response = self._make_request(f'/Users/{self.user_id}/Items', params)
-            if not response:
-                return []
-            
             tracks = []
-            for item in response.get('Items', []):
+            start_index = 0
-                tracks.append(JellyfinTrack(item, self))
+            limit = 1000
+
+            while True:
+                params = {
+                    'ParentId': playlist_id,
+                    'IncludeItemTypes': 'Audio',
+                    'Recursive': True,
+                    'Fields': 'AlbumId,ArtistItems,Path,MediaSources',
+                    'SortBy': 'SortName',
+                    'SortOrder': 'Ascending',
+                    'StartIndex': start_index,
+                    'Limit': limit,
+                }
+
+                response = self._make_request(f'/Users/{self.user_id}/Items', params)
+                if not response:
+                    break
+
+                batch = response.get('Items', [])
+                for item in batch:
+                    tracks.append(JellyfinTrack(item, self))
+
+                if len(batch) < limit:
+                    break  # Last page
+                start_index += limit
 
             logger.debug(f"Retrieved {len(tracks)} tracks from playlist {playlist_id}")
             return tracks