feat(build): add lower-aware put helper

Generate ui::put(slot, view) for lower-aware slot HTML updates and move examples/docs/contracts to that ergonomic path instead of hand-composing slot.html(render(...)).

req: dx/006

req: component/003

req: runtime/001

req: examples/003

examples/kanban/src/main.rs

@@ -138,13 +138,13 @@ async fn interact(
 // req: push/001 req: push/003 req: examples/001
 async fn events(Query(params): Query<BTreeMap<String, String>>) -> impl IntoResponse {
     if params.contains_key("once") {
-        let effect = slots::presence.html(ui::render(&Presence { count: 1 }));
+        let effect = ui::put(slots::presence, &Presence { count: 1 });
         return sse(stream::iter([Ok::<_, Infallible>(effect.into_batch(ui::BUILD_FINGERPRINT))]).boxed());
     }
 
     let batches = stream::unfold(1_u64, |count| async move {
         tokio::time::sleep(Duration::from_secs(4)).await;
-        let effect = slots::presence.html(ui::render(&Presence { count }));
+        let effect = ui::put(slots::presence, &Presence { count });
         Some((Ok::<_, Infallible>(effect.into_batch(ui::BUILD_FINGERPRINT)), count + 1))
     })
     .boxed();
@@ -206,7 +206,7 @@ fn registry(state: Arc<AppState>) -> impl DispatchRegistry {
 
 fn board_effects(board: &BoardState, notice: &'static str) -> impl IntoEffect {
     (
-        slots::board.html(ui::render(&board_view(board))),
+        ui::put(slots::board, &board_view(board)),
         slots::notice.text(notice),
         forms::create_card.clear("title"),
     )