fix: implement stream playback cleaner structure

js/src/api/client.ts

@@ -44,9 +44,11 @@ class ApiClient {
     path: string,
     body?: unknown,
   ): Promise<Response> {
-    const headers: Record<string, string> = {
-      "Content-Type": "application/json",
-    };
+    const headers: Record<string, string> = {};
+
+    if (body) {
+      headers["Content-Type"] = "application/json";
+    }
 
     const token = this.config.getToken();
     if (token) {
@@ -115,7 +117,8 @@ class ApiClient {
       "GET",
       `/particles/${objectId}/download`,
     );
-    return response.url;
+    const data = await response.json();
+    return data.url;
   }
 
   // --- Depot ---