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/components/marketing/WaitlistForm.tsx

@@ -57,7 +57,7 @@ export default function WaitlistForm({ className = "", onSuccess }: WaitlistForm
             <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M5 13l4 4L19 7" />
           </svg>
         </div>
-        <h3 className="text-2xl font-bold text-[#1a1a1a] mb-2" style={{ fontFamily: "'Cormorant Garamond', Georgia, serif" }}>
+        <h3 className="text-2xl font-bold text-[#1a1a1a] mb-2" style={{ fontFamily: "var(--font-fraunces)" }}>
           You&apos;re on the list!
         </h3>
         <p className="text-[#6b8f71]">