feat: initial project setup for Meme Studio

Next.js 14 App Router application for managing homophone pun game levels:

- Better Auth with Prisma adapter for authentication
- MySQL database with Prisma ORM
- Level CRUD operations with drag-and-drop reordering
- Tencent COS integration for image uploads
- shadcn/ui components with Tailwind CSS
- TanStack Query for server state management

app/(dashboard)/layout.tsx

@@ -0,0 +1,16 @@
+import { Sidebar } from '@/components/layout/sidebar'
+
+export default function DashboardLayout({
+  children,
+}: {
+  children: React.ReactNode
+}) {
+  return (
+    <div className="flex h-screen bg-gray-100">
+      <Sidebar />
+      <main className="flex-1 overflow-auto">
+        {children}
+      </main>
+    </div>
+  )
+}