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/components/landing/Stack.vue

@@ -8,17 +8,18 @@ const copy = useCopy()
 
 <template>
   <section id="stack" :style="{ background: t.bg, color: t.fg, scrollMarginTop: '72px' }">
-    <LandingContainer pad="140px 64px">
+    <LandingContainer pad="clamp(56px, 8vw, 140px) clamp(20px, 5vw, 64px)">
       <LandingSectionLabel :label="copy.stack.label" />
-      <div :style="{ display: 'grid', gridTemplateColumns: '1.1fr 1fr', gap: '80px', alignItems: 'end', marginBottom: '56px' }">
+      <div class="stack-intro-grid" :style="{ display: 'grid', gap: '80px', alignItems: 'end', marginBottom: '56px' }">
         <h2 :style="{ fontFamily: '\'Inter Tight\', sans-serif', fontWeight: 600, fontSize: 'clamp(36px, 4.4vw, 64px)', letterSpacing: '-0.032em', lineHeight: 1.0, margin: 0, textWrap: 'balance', color: t.fg }">{{ copy.stack.heading }}</h2>
         <p :style="{ fontFamily: '\'Inter\', sans-serif', fontSize: '20px', lineHeight: 1.5, maxWidth: '480px', color: t.fgMuted, margin: 0, textWrap: 'pretty' }">{{ copy.stack.lede }}</p>
       </div>
       <div>
         <div
           v-for="(row, i) in copy.stack.rows" :key="i"
+          class="stack-row-grid"
           :style="{
-            display: 'grid', gridTemplateColumns: '1.1fr 1.6fr 1.3fr',
+            display: 'grid',
             gap: '24px', padding: '24px 0',
             borderTop: i === 0 ? `1px solid ${t.borderStrong}` : 'none',
             borderBottom: `1px solid ${t.border}`,
@@ -33,3 +34,23 @@ const copy = useCopy()
     </LandingContainer>
   </section>
 </template>
+
+<style scoped>
+.stack-intro-grid {
+  grid-template-columns: 1.1fr 1fr;
+}
+
+.stack-row-grid {
+  grid-template-columns: 1.1fr 1.6fr 1.3fr;
+}
+
+@media (max-width: 768px) {
+  .stack-intro-grid {
+    grid-template-columns: 1fr;
+  }
+
+  .stack-row-grid {
+    grid-template-columns: 1fr;
+  }
+}
+</style>