Add Contract Studio homepage section and update hero

- Add ContractStudioSection with animated IDE mockup (PolkaSwap DEX
  contract), output panel, and 3 feature cards with illustrations
  (Dual Compiler, OpenZeppelin Ready, Native Deploy)
- Position as second section after hero for maximum visibility
- Hero: update badge to "New: Contract Studio is live" linking to
  /studio, add dual CTA buttons (Open Studio + Extrinsic Builder),
  update subtitle to cover both Builder and Studio

Author: itsyogesh

app/(marketing)/page.tsx

@@ -1,6 +1,7 @@
 import { HeroSection } from "@/components/sections/hero-section";
 import { WhyDevelopers } from "@/components/sections/why-developers";
 import { ExtrinsicBuilderSection } from "@/components/sections/extrinsic-builder";
+import { ContractStudioSection } from "@/components/sections/contract-studio";
 import { DappBuildersSection } from "@/components/sections/dapp-builders";
 import { SubstrateUtilitiesSection } from "@/components/sections/substrate-utilities";
 import { TestimonialsSection } from "@/components/sections/testimonials";
@@ -9,6 +10,7 @@ export default function Page() {
   return (
     <>
       <HeroSection />
+      <ContractStudioSection />
       <WhyDevelopers />
       <ExtrinsicBuilderSection />
       <DappBuildersSection />