refine v3 mastery status column alignment

Center-align the mastery status column in the v3 module table to keep row content visually consistent in print output.

Made-with: Cursor

resources/views/exam-analysis/pdf-report-v3.blade.php

@@ -918,6 +918,7 @@
         .module-table td:nth-child(1) { text-align: center; }
         .module-table td:nth-child(2),
         .module-table td:nth-child(3),
+        .module-table td:nth-child(4),
         .module-table td:nth-child(5) { text-align: center; white-space: nowrap; }
         .module-table td:nth-child(6) { font-size: 11px; color: #334155; }
         .module-table tbody tr:nth-child(even) td { background: #fcfdff; }