feat(justine): isolate design system — verbatim CSS + (justine) route group

- Add app/styles/justine/01-homepage.css: rules from 01_homepage.html scoped to [data-justine]
- Replace app/(marketing) with app/(justine): layout wraps data-justine + Plus Jakarta
- JustineHomePage/Nav/Footer: original class names (btn-ink, hero-grid, …) + inline styles from HTML
- Remove app/justine-marketing.css; move /features /pricing /privacy /terms under (justine)

Made-with: Cursor

app/(justine)/layout.tsx

@@ -0,0 +1,47 @@
+import type { Metadata } from "next";
+import { Plus_Jakarta_Sans } from "next/font/google";
+import { homepage } from "@/marketing/content/homepage";
+import { JustineNav } from "@/marketing/components/justine/JustineNav";
+import { JustineFooter } from "@/marketing/components/justine/JustineFooter";
+import "../styles/justine/01-homepage.css";
+
+const justineJakarta = Plus_Jakarta_Sans({
+  subsets: ["latin"],
+  weight: ["400", "500", "600", "700", "800"],
+  variable: "--font-justine-jakarta",
+  display: "swap",
+});
+
+export const metadata: Metadata = {
+  title: homepage.meta.title,
+  description: homepage.meta.description,
+  openGraph: {
+    title: homepage.meta.title,
+    description: homepage.meta.description,
+    url: "https://www.vibnai.com",
+    siteName: "VIBN",
+    type: "website",
+  },
+  twitter: {
+    card: "summary_large_image",
+    title: homepage.meta.title,
+    description: homepage.meta.description,
+  },
+};
+
+export default function JustineLayout({
+  children,
+}: {
+  children: React.ReactNode;
+}) {
+  return (
+    <div
+      data-justine
+      className={`${justineJakarta.variable} flex min-h-screen flex-col`}
+    >
+      <JustineNav />
+      <main>{children}</main>
+      <JustineFooter />
+    </div>
+  );
+}