docs: add modular Node.js AWS S3 migration client implementation

pages/sdk/auto-drive/s3_layer.mdx

@@ -343,3 +343,41 @@ Auto Drive itself uses these helpers, so you get the same delimiter folding, pag
 - Network timeouts may be longer than traditional S3; configure your SDK accordingly
 
 This S3 layer provides a familiar interface while leveraging the benefits of decentralized storage, making it easy to migrate existing S3-based applications — and S3-compatible tooling like rclone and the AWS CLI — to Auto Drive.
+
+---
+
+## AWS S3 Migration Quickstart (Node.js Example)
+
+Below is a clean, minimal implementation showing how to route an existing AWS S3 SDK workflow to the Auto Drive S3 API layer using the official `@aws-sdk/client-s3` package.
+
+```javascript
+const { S3Client, PutObjectCommand } = require("@aws-sdk/client-s3");
+
+// Initialize the S3 Client pointed at the Auto Drive Endpoint
+const autoDriveClient = new S3Client({
+  region: "us-east-1",
+  endpoint: "[https://public.auto-drive.autonomys.xyz/s3](https://public.auto-drive.autonomys.xyz/s3)", // Official Auto Drive S3 gateway URL
+  credentials: {
+    accessKeyId: "ANY_ANY_PLACEHOLDER_STRING", // Can be set to any arbitrary value
+    secretAccessKey: "ANY_ANY_PLACEHOLDER_STRING",
+  },
+  forcePathStyle: true,
+});
+
+async function uploadToPermanentStorage(bucketName, fileKey, fileBuffer) {
+  const command = new PutObjectCommand({
+    Bucket: bucketName,
+    Key: fileKey,
+    Body: fileBuffer,
+  });
+
+  try {
+    const response = await autoDriveClient.send(command);
+    console.log("🔒 Data written permanently to Autonomys!");
+    console.log("Decentralized ETag (CID Mapping):", response.ETag);
+    return response;
+  } catch (error) {
+    console.error("Migration Upload Error:", error);
+    throw error;
+  }
+}