Request to Add Jakarta Region to AWS Amplify

### Before opening, please confirm:

- [X] I have checked to see if my question is addressed in the [FAQ](https://github.com/aws-amplify/amplify-hosting/blob/master/FAQ.md).
- [X] I have [searched for duplicate or closed issues](https://github.com/aws-amplify/amplify-hosting/issues?q=is%3Aissue+).
- [X] I have removed any sensitive information from my code snippets and submission.

### Amplify Hosting feature

Performance mode

### Is your feature request related to a problem? Please describe:

I would like to request the addition of the Jakarta region (ap-southeast-3) to AWS Amplify.
As a developer based in Southeast Asia, having this region available would provide better performance and lower latency for my applications.

Could you kindly look into adding Jakarta as a supported region for AWS Amplify?

Thank you for your consideration!

### Describe how you'd like this feature to work

When creating or managing an Amplify project, I should see "ap-southeast-3 (Jakarta)" as an available region option during the setup process. All backend services, such as AppSync, Lambda, and S3, should also be provisioned in the Jakarta region.

No files, tests, or entry points are named. Start by locating where Amplify Hosting defines available AWS regions and how AppSync, Lambda, and S3 regions are provisioned; confirm what changes are required for ap-southeast-3 (Jakarta) to appear during setup and work across those services.

Written by the indexing model from the issue text.