fix(core): Improve nested DNS record management and worker script multipart handling

ts/cloudflare.classes.workermanager.ts

@@ -22,11 +22,15 @@ export class WorkerManager {
     }
     
     try {
-      // Use the official client to create/update the worker
+      // Use the official client to create/update the worker (upload script content)
       await this.cfAccount.apiAccount.workers.scripts.content.update(workerName, {
         account_id: this.cfAccount.preselectedAccountId,
-        "CF-WORKER-BODY-PART": workerScript,
-        metadata: {}
+        // name the multipart part for the script code
+        metadata: { body_part: 'script' },
+        /* header to indicate which part contains the script */
+        'CF-WORKER-BODY-PART': 'script',
+        // include the actual script as a form part named 'script'
+        script: workerScript,
       });
       
       // Create a new worker instance