fix(excalidraw): send ready signal immediately (fix deadlock: iframe waited for init, parent waited for ready)

frontend/excalidraw-editor.html

@@ -134,6 +134,9 @@
       window.parent.postMessage(msg, "*");
     }
 
+    // Signal that the iframe is loaded and ready to receive init data
+    sendToParent({ type: "ready" });
+
     function markDirty() {
       if (!isDirty) {
         isDirty = true;
@@ -186,7 +189,6 @@
         if (api) {
           excalidrawAPI = api;
           loadingEl.classList.add("hidden");
-          sendToParent({ type: "ready" });
           if (theme === "dark") {
             api.updateScene({ appState: { theme: "dark" } });
           }