fix(FN-4112): remove mobile preset grid scroll cap

- Remove the inner preset grid max-height and overflow cap in the New Agent dialog mobile layout
- Add a dashboard CSS regression test that asserts the mobile media block keeps the preset grid fully visible
- Add a patch changeset for @runfusion/fusion covering the mobile blank-space fix

Fusion-Task-Id: FN-4112

packages/dashboard/app/components/NewAgentDialog.css

@@ -670,4 +670,9 @@
   .agent-dialog-interview-btn {
     width: 100%;
   }
+
+  .agent-presets-grid {
+    max-height: none;
+    overflow-y: visible;
+  }
 }