feat(website): gated coming-soon holding page with email signup

Add a standalone bilingual /coming-soon page (branded, dark, email signup
via mailto:info@dezky.eu, fires a waitlist-signup Umami event, noindex) plus
a global middleware that redirects every route to the locale-correct holding
page while NUXT_PUBLIC_COMING_SOON=true.

- Env-gated (default off, so dev and the live site are unaffected); flip the
  env in Coolify to show/hide the holding page with no code change.
- Preview the real site behind the gate via ?preview=<previewToken>
  (NUXT_PUBLIC_PREVIEW_TOKEN), which sets a 7-day cookie.
- Locale-preserving redirects (/da/* -> /da/coming-soon), no loops.

apps/website/middleware/coming-soon.global.ts

@@ -0,0 +1,25 @@
+// Holding-page gate. While NUXT_PUBLIC_COMING_SOON=true, every route is
+// redirected to the locale-appropriate /coming-soon page so the unfinished
+// site stays hidden. Flip the env to false (in Coolify) to launch — no code
+// change. The team can preview the real site via ?preview=<token>, which sets
+// a short-lived cookie so subsequent navigation stays unlocked.
+export default defineNuxtRouteMiddleware((to) => {
+  const config = useRuntimeConfig()
+  if (!config.public.comingSoon) return
+
+  // Never redirect the holding page itself (avoids a loop).
+  if (to.path === '/coming-soon' || to.path === '/da/coming-soon') return
+
+  const token = config.public.previewToken as string
+  const bypass = useCookie<string | null>('dz_preview', {
+    maxAge: 60 * 60 * 24 * 7, sameSite: 'lax', path: '/',
+  })
+  if (token && to.query.preview === token) {
+    bypass.value = '1'
+    return
+  }
+  if (bypass.value === '1') return
+
+  const isDa = to.path === '/da' || to.path.startsWith('/da/')
+  return navigateTo(isDa ? '/da/coming-soon' : '/coming-soon')
+})