fix: improve Cancel button contrast in AI disclaimer modal

Changed variant from 'outline' to 'secondary' for better visibility
in dark theme. The outline variant had insufficient contrast making
the button difficult to read.

src/pages/NewIssue/index.tsx

@@ -162,7 +162,7 @@ export default function NewIssue() {
               </Button>
               <Button
                 onClick={() => navigate("/")}
-                variant="outline"
+                variant="secondary"
                 className="flex-1"
               >
                 Cancel