App reorganization

app/(dev)/layout.tsx

@@ -0,0 +1,7 @@
+import type { ReactNode } from "react";
+
+// Development-only previews (e.g. `/components-preview`) — no public chrome.
+// Routes here are gated by NODE_ENV checks at the page level.
+export default function DevLayout({ children }: { children: ReactNode }) {
+  return <main className="flex-1">{children}</main>;
+}