fix(css): remove stale forum page imports

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

assets/css/frontend/pages.css

@@ -1,6 +1,4 @@
 @import url("pages/base.css");
-@import url("pages/board-cards.css");
-@import url("pages/topic-rows.css");
 @import url("pages/sidebar.css");
 @import url("pages/empty-state.css");
 @import url("pages/submit.css");