fix iframe resizing (#19)

* reshuffle build / start scripts

* fix resize logic

* prettier

* extract RESOURCE_URI_META_KEY constant

* Update message-transport.ts

* Update package.json

specification/draft/apps.mdx

@@ -316,7 +316,7 @@ function sendRequest(method: string, params: any) {
       if (event.data?.id === id) {
         window.removeEventListener('message', listener);
         if (event.data?.result) {
-          resolve(true);
+          resolve(event.data?.result);
         } else if (event.data?.error) {
           reject(new Error(event.data.error));
         }