Add stelab adaptor

[mtuchi]

Summary

This PR adds stelab adaptor with basic functions, get, post and request

Details

Add technical details of what you've changed (and why).

AI Usage

Please disclose how you've used AI in this work (it's cool, we just want to
know!):

• I have used Claude Code
• I have used another model
• I have not used AI

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Review Checklist

Before merging, the reviewer should check the following items:

• Does the PR do what it claims to do?
• If this is a new adaptor, added the adaptor on marketing website ?
• If this PR includes breaking changes, do we need to update any jobs in
  production? Is it safe to release?
• Are there any unit tests?
• Is there a changeset associated with this PR? Should there be? Note that
  dev only changes don't need a changeset.
• Have you ticked a box under AI Usage?