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/pages/partners.vue

@@ -6,6 +6,7 @@ definePageMeta({ layout: 'page' })
 
 const t = useTheme()
 const copy = useCopy()
+const localePath = useLocalePath()
 const c = computed(() => copy.value.pages.partners)
 
 const openFaq = ref<number | null>(0)
@@ -196,7 +197,7 @@ useHead({ title: () => `${copy.value.pages.partners.label} · dezky` })
           <p :style="{ marginTop: '20px', fontFamily: '\'Inter\', sans-serif', fontSize: '18px', lineHeight: 1.6, color: t.fgMuted, maxWidth: '420px', textWrap: 'pretty' }">{{ c.form.lede }}</p>
           <button
             :style="{ marginTop: '28px', background: 'transparent', border: 'none', padding: 0, cursor: 'pointer', fontFamily: '\'Inter\', sans-serif', fontSize: '15px', color: t.fgMuted, textDecoration: 'underline', textUnderlineOffset: '3px' }"
-            @click="navigateTo('/demo')"
+            @click="navigateTo(localePath('/demo'))"
           >{{ c.cta }} →</button>
         </div>