feat(website): bilingual i18n (English default, Danish at /da) + SEO

Add @nuxtjs/i18n: English is the default locale (no prefix), Danish lives
under /da (prefix_except_default). Both server-rendered and indexed with
hreflang alternates + per-locale canonical (useLocaleHead in app.vue).
First-visit browser language is auto-detected and remembered in the
i18n_redirected cookie (redirectOn root).

- Keep the hand-authored COPY object; useLang/useCopy now read the i18n
  locale; useLocalizeHref/useLangToggle added. Every internal link is
  localized so navigation stays in-locale.
- Clear segmented EN|DA language switcher (active segment filled) replacing
  the ambiguous "en · da" pill.
- SEO: useSeoMeta defaults are locale-aware; og:image switches per locale
  (English / Danish share card); favicon links; robots.txt + sitemap.xml;
  env-aware siteUrl/baseUrl (localhost in dev, dezky.eu in prod).
- Update the cookie policy (dezky-lang -> i18n_redirected).
- Gate the Traefik wss:443 HMR behind DEZKY_TRAEFIK so localhost dev/DevTools
  connect over plain ws (fixes the DevTools disconnect loop).

apps/website/utils/landingCopy.ts

@@ -457,7 +457,7 @@ export const COPY = {
         tableHeading: 'Cookies vi bruger',
         tableCols: ['Cookie', 'Formål', 'Varighed'],
         table: [
-          ['dezky-lang', 'Husker dit valgte sprog (dansk/engelsk)', '12 måneder'],
+          ['i18n_redirected', 'Husker dit valgte sprog (dansk/engelsk)', '1 år'],
           ['Loginsession', 'Holder dig logget ind på app.dezky.eu', 'Session'],
         ] as [string, string, string][],
         contactHeading: 'Kontakt',
@@ -959,7 +959,7 @@ export const COPY = {
         tableHeading: 'Cookies we use',
         tableCols: ['Cookie', 'Purpose', 'Duration'],
         table: [
-          ['dezky-lang', 'Remembers your chosen language (Danish/English)', '12 months'],
+          ['i18n_redirected', 'Remembers your chosen language (Danish/English)', '1 year'],
           ['Login session', 'Keeps you signed in to app.dezky.eu', 'Session'],
         ] as [string, string, string][],
         contactHeading: 'Contact',