Simplify Iris app initialization and task updates

app/examples/transcript.rs

@@ -158,7 +158,7 @@ fn fold_event(items: Vec<Item>, seq: u64) -> Vec<Item> {
 ";
 
 impl DesktopAppState for Client {
-    fn new(mut ui_state: DesktopUiState, rsc: &mut StdRsc<Self>, _: Proxy<Self::Event>) -> Self {
+    fn new(mut ui_state: DesktopUiState, rsc: &mut StdRsc<Self>) -> Self {
         let mut screen = ai_app::ui::build(rsc, &mut ui_state, synthetic_rows());
         screen.push_row(
             rsc,