feat(website): responsive / mobile layouts

Make the marketing site mobile-friendly across every page and section.
Desktop appearance is unchanged; all breakpoint logic targets <=768px.

- Fluid section padding via clamp(); equal grids use auto-fit/minmax,
  asymmetric grids stack to one column via scoped-CSS media queries
- Nav: real hamburger menu on mobile (links, lang toggle, login, CTA)
- ProductMockup: scales the whole dashboard to fit (zoom) instead of
  reflowing its internals into a tall stack
- Lower oversized heading clamp() minimums so titles no longer overflow
  at ~390px (hero, page headers, final CTA, brand cover/chapter)
- HowItWorks: row-gap when steps stack so node markers clear the text
- Compare + partners tables: stacked rows now label each value with its
  column (Dezky vs hyperscaler / CSP) instead of an ambiguous header
- Footer columns, tiers, calculator and tables stack cleanly on mobile

apps/website/pages/roadmap.vue

@@ -13,11 +13,13 @@ useHead({ title: () => `${copy.value.pages.roadmap.label} · dezky` })
 <template>
   <LandingPageHeader :label="c.label" :title="c.title" :intro="c.intro" />
 
-  <LandingContainer pad="56px 64px 160px">
-    <div :style="{ display: 'grid', gridTemplateColumns: 'repeat(3, 1fr)', gap: '0', border: `1px solid ${t.border}`, borderRadius: '4px', overflow: 'hidden' }">
+  <LandingContainer pad="clamp(56px, 8vw, 56px) clamp(20px, 5vw, 64px) clamp(80px, 12vw, 160px)">
+    <div :style="{ display: 'grid', gridTemplateColumns: 'repeat(auto-fit, minmax(min(100%, 240px), 1fr))', gap: '0', border: `1px solid ${t.border}`, borderRadius: '4px', overflow: 'hidden' }">
       <div
         v-for="(col, i) in c.columns" :key="i"
-        :style="{ padding: '32px 28px', borderLeft: i === 0 ? 'none' : `1px solid ${t.border}`, background: t.surface, minHeight: '260px' }"
+        class="roadmap-col"
+        :class="{ 'roadmap-col--first': i === 0 }"
+        :style="{ padding: '32px 28px', background: t.surface, minHeight: '260px', '--roadmap-border': t.border }"
       >
         <div :style="{ display: 'flex', alignItems: 'center', gap: '10px', marginBottom: '24px' }">
           <span :style="{ width: '6px', height: '6px', borderRadius: '999px', background: i === 0 ? t.signal : t.fgDim }" />
@@ -33,3 +35,22 @@ useHead({ title: () => `${copy.value.pages.roadmap.label} · dezky` })
     </div>
   </LandingContainer>
 </template>
+
+<style scoped>
+.roadmap-col {
+  border-left: 1px solid var(--roadmap-border);
+  border-top: none;
+}
+.roadmap-col--first {
+  border-left: none;
+}
+@media (max-width: 768px) {
+  .roadmap-col {
+    border-left: none;
+    border-top: 1px solid var(--roadmap-border);
+  }
+  .roadmap-col--first {
+    border-top: none;
+  }
+}
+</style>