polish: consolidate typography to next/font variables, add atelier utility classes

- Remove Google Fonts @import from 4 components (SiteHeader, LandingPageWrapper,
  TestimonialsAndCTA, FeaturesAndStats) — eliminate render-blocking external
  request and font flash
- Replace all unloaded Cormorant Garamond / Playfair Display / DM Sans /
  Plus Jakarta Sans references with the existing next/font variables
  (Fraunces, Manrope, Fragment_Mono) — visual coherence with the design system
- Update 9 pages (blog, brands, changelog, maintenance, protected-example,
  roadmap, security, waitlist, WaitlistForm) to use the loaded Fraunces
- Fix dead --font-geist / --font-jetbrains-mono references in
  admin-design-system.css (now point to --font-manrope / --font-fragment-mono
  which are actually loaded)
- Add atelier-pill, atelier-numerals, atelier-fineprint, atelier-canvas-soft
  utility classes; .atelier-input:focus-visible refined ring
- Add .ha-field-textarea, .ha-scroll, .ha-skeleton to admin design system
- Extend prefers-reduced-motion guard to atelier-enter/stagger/shimmer
- Apply atelier-fineprint to login/not-found/error pages for consistency
- No structural changes; build passes, 0 type errors

src/app/changelog/page.tsx

@@ -132,7 +132,7 @@ export default function ChangelogPage() {
       <main className="max-w-4xl mx-auto px-6 py-16">
         {/* Hero */}
         <div className="text-center mb-16">
-          <h1 className="text-5xl font-bold text-[#1a1a1a] mb-4" style={{ fontFamily: "'Cormorant Garamond', Georgia, serif" }}>
+          <h1 className="text-5xl font-bold text-[#1a1a1a] mb-4" style={{ fontFamily: "var(--font-fraunces)" }}>
             Changelog
           </h1>
           <p className="text-xl text-[#6b8f71] max-w-2xl mx-auto">