feat(website): footer sub-pages + shared page layout

Wire every footer link to a real route. Adds a shared `page` layout (Nav +
content + Footer), reusable PageHeader/ComingSoon components, six content pages
(about, contact, brand, roadmap, changelog, migration), and a dynamic [slug]
catch-all for the not-yet-built pages — unknown slugs 404, legal slugs get a
distinct "contact us" body.

Footer links repointed from dead "#" to real paths; section anchors ("/#suite")
smooth-scroll on the homepage and route home + scroll from a sub-page; logo
links home. Page copy (da + en) added under COPY.pages.

apps/website/components/landing/ComingSoon.vue

@@ -0,0 +1,19 @@
+<script setup lang="ts">
+// Placeholder body for not-yet-built sub-pages. Shows the page title under a
+// "coming soon" eyebrow, an explanatory line, and a demo CTA. Legal pages pass
+// the legal-specific body instead of the generic one.
+import { useRoute } from 'vue-router'
+import { useCopy, goToSection } from '~/composables/useLanding'
+
+defineProps<{ title: string, body: string }>()
+
+const copy = useCopy()
+const route = useRoute()
+</script>
+
+<template>
+  <LandingPageHeader :label="copy.pages.comingSoonKicker" :title="title" :intro="body" />
+  <LandingContainer pad="48px 64px 160px">
+    <LandingBtn variant="primary" size="lg" @click="goToSection('#final-cta', route.path)">{{ copy.pages.ctaDemo }} →</LandingBtn>
+  </LandingContainer>
+</template>