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/signed-out.vue

@@ -1,4 +1,5 @@
 <script setup lang="ts">
+const operatorHost = new URL(useRuntimeConfig().public.operatorUrl).host
 // Sign-out landing for the operator portal. /api/auth/sign-out cleared the
 // local session and bounced through Authentik's end-session endpoint, which
 // ended the IdP session. By the time we render here the user has no
@@ -24,7 +25,7 @@ function signInAgain() {
         ready — Authentik will ask for fresh credentials.
       </p>
       <button class="primary" type="button" @click="signInAgain">Sign in again</button>
-      <p class="hint">operator.dezky.local</p>
+      <p class="hint">{{ operatorHost }}</p>
     </div>
   </div>
 </template>