Fragment Grid Taxonomy Query Fix

Previously, taxonomy archives for themes and topics were showing every Fragment, regardless of tag. The cause was that fragment-grid.php ignored the $query object passed from taxonomy.php, instead running a new unfiltered WP_Query. This was corrected by updating the fragment grid template to use the incoming query, ensuring only fragments tagged with the active taxonomy term are displayed. The fix brings fragment behavior in line with chapters and restores proper taxonomy filtering site-wide.