add webview threaded api

pkgs/webview-ui/app/src/message.ts

@@ -0,0 +1,22 @@
+const deserialize = (fn: Function) => (str: string) => {
+  try {
+    fn(JSON.parse(str));
+  } catch (e) {
+    alert(`Error parsing JSON: ${e}`);
+  }
+};
+
+export const PYAPI = {
+  list_machines: {
+    dispatch: (data: null) =>
+      // @ts-ignore
+      window.webkit.messageHandlers.gtk.postMessage({
+        method: "list_machines",
+        data,
+      }),
+    receive: (fn: (response: string[]) => void) => {
+      // @ts-ignore
+      window.clan.list_machines = deserialize(fn);
+    },
+  },
+};