refactor: update icon usage to use mdi imports for consistency

src/views/errors/NetworkError.vue

@@ -3,12 +3,13 @@
     code="NETWORK"
     color="warning"
     description="無法連線到伺服器，請檢查網路或稍後再試。"
-    icon="mdi-wifi-off"
+    :icon="mdiWifiOff"
     title="網路連線異常"
   />
 </template>
 
 <script setup lang="ts">
+import { mdiWifiOff } from '@mdi/js'
 import ErrorShell from './ErrorShell.vue'
 </script>