test: await ky create route response

[xgcing]

Summary

/claim #2

This tightens the existing ky-backed create route regression test:

• await the POST /things/create ky request before listing things
• assert the create route returns { ok: true }
• verify the persisted thing name and description after listing

The previous test fired the ky POST without awaiting it, so the immediate list request could race the create request and make the coverage nondeterministic.

Verification

• git diff --check

I could not run the Bun test suite locally because bun is not installed on PATH.