make fullstack hello world compile

packages/dioxus/src/lib.rs

@@ -57,6 +57,9 @@ pub mod prelude {
     pub use dioxus_hot_reload::{self, hot_reload_init};
 
     pub use dioxus_core;
+
+    #[cfg(feature = "fullstack")]
+    pub use dioxus_fullstack::prelude::*;
 }
 
 #[cfg(feature = "web")]