chore: Nuxt 4 upgrade (#7426)

frontend/app/plugins/dark-mode.client.ts

@@ -0,0 +1,20 @@
+import { useDark } from "@vueuse/core";
+
+export default defineNuxtPlugin((nuxtApp) => {
+  const isDark = useDark({
+    onChanged: (v) => {
+      console.log(`changing theme to ${v ? "dark" : "light"} using @vueuse/useDark`);
+      const $vuetify = nuxtApp.vueApp.$nuxt.$vuetify;
+      if ($vuetify)
+        $vuetify.theme.global.name.value = v ? "dark" : "light";
+    },
+  });
+
+  nuxtApp.hook("vuetify:ready", (vuetify) => {
+    vuetify.theme.global.name.value = isDark.value ? "dark" : "light";
+  });
+
+  return {
+    provide: {},
+  };
+});