fix(operator,portal): env-driven sign-out URLs + host labels (no more .local in prod)

Operator sign-out hardcoded the dev Authentik end-session URL, so prod
logout landed on auth.dezky.local. Mirror the portal's env-driven pattern
(NUXT_PUBLIC_AUTH_URL/NUXT_PUBLIC_OPERATOR_URL with .local fallbacks).
Expose authUrl/operatorUrl via public runtimeConfig and use them for the
Authentik admin links and the cosmetic host labels (sidebar, eyebrows,
auth-page hints). Portal: signed-out + webmail copy now derive their hosts
from runtime config (new public.mailUrl, NUXT_PUBLIC_MAIL_URL in prod).

apps/operator/pages/index.vue

@@ -1,4 +1,5 @@
 <script setup lang="ts">
+const operatorHost = new URL(useRuntimeConfig().public.operatorUrl).host
 import type { Tenant } from '~/types/tenant'
 import type { Partner } from '~/types/partner'
 import type { PlatformUser } from '~/types/user'
@@ -65,7 +66,7 @@ function fmtDate(d: string) {
 <template>
   <div>
     <PageHeader
-      eyebrow="Operator · operator.dezky.local"
+      :eyebrow="`Operator · ${operatorHost}`"
       title="Platform overview"
       :subtitle="`${stats.tenants} tenants · ${stats.partners} partners · ${stats.users} platform users`"
     >