added a beta access feature

web/src/components/BetaGate.tsx

@@ -0,0 +1,37 @@
+import { type ReactNode, useEffect, useState } from "react";
+import { Navigate, useLocation } from "react-router-dom";
+
+const STORAGE_KEY = "skymoney_beta_access";
+
+type Props = {
+  children: ReactNode;
+};
+
+export function BetaGate({ children }: Props) {
+  const location = useLocation();
+  const [hasAccess, setHasAccess] = useState<boolean | null>(null);
+
+  useEffect(() => {
+    setHasAccess(localStorage.getItem(STORAGE_KEY) === "true");
+  }, []);
+
+  if (location.pathname === "/beta") {
+    return <>{children}</>;
+  }
+
+  if (hasAccess === null) {
+    return (
+      <div className="flex min-h-[40vh] items-center justify-center text-sm muted">
+        Checking access…
+      </div>
+    );
+  }
+
+  if (!hasAccess) {
+    return <Navigate to="/beta" replace />;
+  }
+
+  return <>{children}</>;
+}
+
+export const betaAccessStorageKey = STORAGE_KEY;