Add open api specs

[sanatik]

Description

(replace me) -> Use the linear generated branch name to automatically attach the issue description as a comment on the PR. If you don't have a linear issue, strongly consider making one! Otherwise, include a meaningful description of the change and why we're making it now.

Checklist:

• All changes in this PR are at least one version backwards compatible, (reverting this PR is safe eg data migrations are backwards compatible).
• I have performed a thorough self-review of my code
• I have commented the code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (README.md, architecture docs, public docs, etc).