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/PageHeader.vue

@@ -0,0 +1,36 @@
+<script setup lang="ts">
+// Shared header for sub-pages: back link, mono eyebrow with signal dot, big
+// title, optional intro. Mirrors the hero/section typography so sub-pages feel
+// like the same site.
+import { useTheme, useCopy } from '~/composables/useLanding'
+
+defineProps<{ label: string, title: string, intro?: string }>()
+
+const t = useTheme()
+const copy = useCopy()
+</script>
+
+<template>
+  <LandingContainer pad="120px 64px 0">
+    <NuxtLink
+      to="/"
+      :style="{ fontFamily: '\'JetBrains Mono\', monospace', fontSize: '12px', color: t.fgMuted, letterSpacing: '0.04em', display: 'inline-flex', alignItems: 'center', gap: '8px' }"
+    >← {{ copy.pages.back }}</NuxtLink>
+
+    <div :style="{ display: 'flex', alignItems: 'center', gap: '12px', marginTop: '48px', marginBottom: '24px' }">
+      <span :style="{ width: '6px', height: '6px', borderRadius: '999px', background: t.signal, boxShadow: `0 0 0 4px ${t.signal}33` }" />
+      <span :style="{ fontFamily: '\'JetBrains Mono\', monospace', fontSize: '12px', color: t.fgMuted, letterSpacing: '0.08em', textTransform: 'uppercase' }">{{ label }}</span>
+    </div>
+
+    <h1 :style="{
+      fontFamily: '\'Inter Tight\', \'Inter\', sans-serif', fontWeight: 600,
+      fontSize: 'clamp(40px, 5.4vw, 76px)', letterSpacing: '-0.035em', lineHeight: 1.0,
+      margin: 0, textWrap: 'balance', color: t.fg, maxWidth: '900px',
+    }">{{ title }}</h1>
+
+    <p
+      v-if="intro"
+      :style="{ marginTop: '32px', maxWidth: '620px', fontFamily: '\'Inter\', sans-serif', fontSize: '20px', lineHeight: 1.5, color: t.fgMuted, textWrap: 'pretty' }"
+    >{{ intro }}</p>
+  </LandingContainer>
+</template>