fix(core): Ensure correct ArrayBuffer return, fix fetch body typing, reorganize node-only tests, and bump tsbuild devDependency

ts/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartrequest',
-  version: '4.3.7',
+  version: '4.3.8',
   description: 'A module for modern HTTP/HTTPS requests with support for form data, file uploads, JSON, binary data, streams, and more.'
 }

ts/core_fetch/request.ts

@@ -71,7 +71,7 @@ export class CoreRequest extends AbstractCoreRequest<
         // Check for Buffer (Node.js polyfills in browser may provide this)
         (typeof Buffer !== 'undefined' && this.options.requestBody instanceof Buffer)
       ) {
-        fetchOptions.body = this.options.requestBody;
+        fetchOptions.body = this.options.requestBody as BodyInit;
         
         // If streaming, we need to set duplex mode
         if (this.options.requestBody instanceof ReadableStream) {

ts/core_node/response.ts

@@ -115,10 +115,12 @@ export class CoreResponse<T = any>
    */
   async arrayBuffer(): Promise<ArrayBuffer> {
     const buffer = await this.collectBody();
-    return buffer.buffer.slice(
+    const sliced = buffer.buffer.slice(
       buffer.byteOffset,
       buffer.byteOffset + buffer.byteLength,
     );
+    // Ensure we return ArrayBuffer, not SharedArrayBuffer
+    return sliced instanceof ArrayBuffer ? sliced : new ArrayBuffer(0);
   }
 
   /**