fix(bookmark): truncate title to 500 chars when archiving

Entry titles can be up to 1000 chars but Bookmark.title is VARCHAR(500).
This caused StringDataRightTruncationError when archiving entries with
long titles.

Author: LeslieLeung

backend/packages/core/glean_core/services/bookmark_service.py

@@ -224,7 +224,7 @@ async def create_bookmark(
         Raises:
             ValueError: If entry not found or validation fails.
         """
-        title = data.title
+        title = data.title[:500] if data.title else data.title
         excerpt = data.excerpt
         entry_id = data.entry_id
         url = data.url