Two corrections to the qry_files filter:
1. Switch from file_count to file_count_all — covers files on presentations
and presenters under the session, not just direct session files.
2. Switch "without files" from eq:0 to is_null — the view uses a LEFT JOIN
so sessions with no files get NULL, never 0.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>