fix(auth): prevent flash of login screen by maintaining loading state while resolving post-auth dashboard routing

vibn-frontend/app/components/auth/AuthFlow.tsx

@@ -12,9 +12,11 @@ function AuthFlowInner({ mode }: { mode: "signin" | "signup" }) {
 
   const [ssoProcessing, setSsoProcessing] = React.useState(false);
   const [ssoToken, setSsoToken] = React.useState<string | null>(null);
+  const [routing, setRouting] = React.useState(false);
 
   useEffect(() => {
     if (status === "authenticated" && session?.user?.email) {
+      setRouting(true);
       const isVibnCodeSSO = searchParams?.get("vibncode") === "true";
 
       if (isVibnCodeSSO) {
@@ -65,7 +67,7 @@ function AuthFlowInner({ mode }: { mode: "signin" | "signup" }) {
     }
   }, [status, session, router, searchParams]);
 
-  if (status === "loading" || ssoProcessing) {
+  if (status === "loading" || ssoProcessing || routing) {
     return (
       <div
         className="new-site-wrapper"