fix: login/registo funcional — signIn NextAuth, SessionProvider, NEXTAUTH_SECRET real, error handling

app/providers.tsx

@@ -0,0 +1,7 @@
+'use client';
+
+import { SessionProvider } from 'next-auth/react';
+
+export default function Providers({ children }: { children: React.ReactNode }) {
+  return <SessionProvider>{children}</SessionProvider>;
+}