fix: handle login failure after registration

src/app/register/page.tsx

@@ -32,9 +32,14 @@ export default function RegisterPage() {
       return;
     }
     // Direct inloggen na registratie
-    await signIn("credentials", { username, password, redirect: false });
+    const loginRes = await signIn("credentials", { username, password, redirect: false });
+    if (loginRes?.error) {
+      // Registratie gelukt maar inloggen mislukt — stuur naar login
+      router.replace("/login");
+    } else {
       router.replace("/");
     }
+  }
 
   return (
     <div className="flex flex-col items-center justify-center min-h-[70vh] px-4">