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/portal/nuxt.config.ts

@@ -49,6 +49,7 @@ export default defineNuxtConfig({
       authUrl: process.env.NUXT_PUBLIC_AUTH_URL,
       portalUrl: process.env.NUXT_PUBLIC_PORTAL_URL,
       bookingUrl: process.env.NUXT_PUBLIC_BOOKING_URL || 'https://booking.dezky.local',
+      mailUrl: process.env.NUXT_PUBLIC_MAIL_URL || 'https://mail.dezky.local',
     },
   },