chore(portal,operator): upgrade to Nuxt 4

Upgrade both Nuxt apps to Nuxt 4.4.6 (vue-tsc 3, TypeScript 5.6, undici 7) and add a root tsconfig.json to each app. Fix the strict-null / noUncheckedIndexedAccess errors surfaced by Nuxt 4's stricter generated tsconfig and vue-tsc 3. Drop the nuxt-oidc-auth pnpm patch (Nuxt 4 fixes the prepare:types crash natively).

apps/portal/pages/admin/branding.vue

@@ -18,6 +18,10 @@ const editTemplate = ref<typeof TEMPLATES[number] | null>(null)
 const subject = ref('')
 const body = ref('')
 const testSent = ref(false)
+function sendTest() {
+  testSent.value = true
+  setTimeout(() => (testSent.value = false), 2500)
+}
 
 const publishOpen = ref(false)
 const publishState = ref<'confirm' | 'publishing' | 'done'>('confirm')
@@ -384,7 +388,7 @@ const renderedBody = computed(() =>
           Reset to default
         </UiButton>
         <div style="flex: 1" />
-        <UiButton variant="secondary" @click="testSent = true; setTimeout(() => testSent = false, 2500)">
+        <UiButton variant="secondary" @click="sendTest">
           <template #leading><UiIcon name="mail" :size="13" /></template>
           {{ testSent ? 'Sent to anne@dezky.com ✓' : 'Send test to me' }}
         </UiButton>