Add login gate, calculation history, and AI markdown download.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/layout.tsx

@@ -4,6 +4,7 @@ import React from "react";
 import Umami from "@/components/umami";
 import PwaProvider from "@/components/pwa/pwa-provider";
 import PwaDisplayMode from "@/components/pwa/pwa-display-mode";
+import { AuthProvider } from "@/components/auth/auth-provider";
 import { ThemeProvider } from "next-themes";
 
 export const metadata: Metadata = {
@@ -53,9 +54,11 @@ export default function RootLayout({
           defaultTheme="system"
           disableTransitionOnChange
         >
-          {children}
-          <PwaDisplayMode />
-          <PwaProvider />
+          <AuthProvider>
+            {children}
+            <PwaDisplayMode />
+            <PwaProvider />
+          </AuthProvider>
         </ThemeProvider>
         <Umami />
       </body>