chore(init): scaffold OpenFrame — Next.js + Bun + shadcn

Initialize OpenFrame project with core scaffold and UI foundation.

- Project scaffold: Next.js 16.1 (App Router) + Bun runtime
- UI: shadcn/ui + TailwindCSS; landing, dashboard, project, and auth UIs
- Video support: provider abstraction (YouTube first), video player page with timestamped comments and custom timeline
- Auth & DB: NextAuth skeleton and Prisma schema (Postgres) included
- UX: dark-mode toggle, full-width layouts, comments sidebar, video route moved to /watch/[videoId]
- Dev: added YouTube iframe integration, custom controls, and TypeScript types
- Next steps: DB migrations, API routes (CRUD), real data wiring, voice-recording & sharing

app/(dashboard)/layout.tsx

@@ -0,0 +1,23 @@
+import { Header } from '@/components/layout';
+// import { auth } from '@/lib/auth';
+
+export default async function DashboardLayout({
+  children,
+}: {
+  children: React.ReactNode;
+}) {
+  // TODO: Uncomment when database is set up
+  // const session = await auth();
+  const mockUser = {
+    name: 'Demo User',
+    email: '[email protected]',
+    image: null,
+  };
+
+  return (
+    <div className="relative flex min-h-screen flex-col">
+      <Header user={mockUser} />
+      <main className="flex-1">{children}</main>
+    </div>
+  );
+}