fix(ui): update memory user when autoLogin enabled (#14018)

Fixes https://github.com/payloadcms/payload/issues/14005

When `autoLogin` is enabled, the Auth Provider's user in memory becomes
stale. This change ensures the user in memory stays up to date if
`autoLogin && !autoLogin.prefillOnly` is set.

packages/ui/src/providers/Auth/index.tsx

@@ -59,6 +59,7 @@ export function AuthProvider({
 
   const {
     admin: {
+      autoLogin,
       autoRefresh,
       routes: { inactivity: logoutInactivityRoute },
       user: userSlug,
@@ -303,6 +304,12 @@ export function AuthProvider({
     void fetchUserOnMount()
   }, [])
 
+  useEffect(() => {
+    if (!user && autoLogin && !autoLogin.prefillOnly) {
+      void fetchFullUserEvent()
+    }
+  }, [user, autoLogin])
+
   useEffect(
     () => () => {
       // remove all timeouts on unmount