feat: unify card runtime and event-driven web ui

scripts/card_runtime_fixture_card.mjs

@@ -0,0 +1,24 @@
+export function mount({ root, state, host }) {
+  const render = (nextState) => {
+    const title = typeof nextState.title === "string" ? nextState.title : "";
+    root.innerHTML = `<div data-fixture-title="${title}">${title}</div>`;
+  };
+
+  render(state);
+  host.setLiveContent({ phase: "mount", title: state.title ?? "" });
+  host.setRefreshHandler(() => {
+    root.dataset.refreshed = "1";
+  });
+
+  return {
+    update({ state: nextState, host: nextHost }) {
+      render(nextState);
+      nextHost.setLiveContent({ phase: "update", title: nextState.title ?? "" });
+    },
+    destroy() {
+      root.dataset.destroyed = "1";
+      root.innerHTML = "";
+      host.setRefreshHandler(null);
+    },
+  };
+}