Update participant and study API routes

src/components/layout.tsx

@@ -0,0 +1,19 @@
+import { PropsWithChildren } from "react";
+import { Sidebar } from "~/components/sidebar";
+import { StudyHeader } from "~/components/study/StudyHeader";
+
+const Layout = ({ children }: PropsWithChildren) => {
+  return (
+    <div className="flex h-screen bg-gradient-to-b from-blue-100 to-white">
+      <Sidebar />
+      <main className="flex-1 overflow-y-auto p-4 pt-16 lg:pt-4">
+        <div className="container mx-auto space-y-4">
+          <StudyHeader />
+          {children}
+        </div>
+      </main>
+    </div>
+  );
+};
+
+export default Layout;