refine v3 module table center alignment

Center-align the focus knowledge column in the v3 module table so printed layout looks balanced and consistent.

Made-with: Cursor

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

@@ -913,7 +913,7 @@
         .module-table th,
         .module-table td { vertical-align: middle; }
         .module-table th:nth-child(6) { vertical-align: middle; }
-        .module-table td:nth-child(6) { vertical-align: top; }
+        .module-table td:nth-child(6) { vertical-align: middle; text-align: center; }
         .module-table th:nth-child(1),
         .module-table td:nth-child(1) { text-align: center; }
         .module-table td:nth-child(2),