feat: add 404 catch-all route with NotFound view

Unmatched URLs now show a glass-card 404 page with a link back
to the dashboard instead of a blank page.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

neode-ui/src/router/index.ts

@@ -185,6 +185,11 @@ const router = createRouter({
         },
       ],
     },
+    {
+      path: '/:pathMatch(.*)*',
+      name: 'not-found',
+      component: () => import('../views/NotFound.vue'),
+    },
   ],
 })