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/ComingSoon.vue

@@ -13,7 +13,7 @@ const route = useRoute()
 
 <template>
   <LandingPageHeader :label="copy.pages.comingSoonKicker" :title="title" :intro="body" />
-  <LandingContainer pad="48px 64px 160px">
+  <LandingContainer pad="clamp(32px, 5vw, 48px) clamp(20px, 5vw, 64px) clamp(56px, 8vw, 160px)">
     <LandingBtn variant="primary" size="lg" @click="goToSection('#final-cta', route.path)">{{ copy.pages.ctaDemo }} →</LandingBtn>
   </LandingContainer>
 </template>