fix(FN-1985): expand agent import skills list on mobile

- Add a mobile max-height rule for .agent-import-skill-list using dynamic viewport units.
- Allow the skills picker to fill available screen space without overflowing the agent import modal.

packages/dashboard/app/styles.css

@@ -31998,6 +31998,10 @@ html .column.drag-over * {
   .agent-import-browse-list {
     max-height: calc(100dvh - 260px);
   }
+
+  .agent-import-skill-list {
+    max-height: calc(100dvh - 380px);
+  }
 }
 
 @media (max-width: 480px) {