In scope:

• set up autoloading for rest api namespace
• initial test set up: wire up unit tests with mediawiki phpunit runner, set up initial end to end test
• generate swagger autodocs
• Investigate/explore what MW rest api does about per endpoint documentation and examples (does mw rest api provide some "framework" for it like for the "action api")
• setup linting: stricter linting than the rest of Wikibase (e.g. enforce strict types in all REST API)
• set up a separate ServiceWiring.php for /repo/rest-api
• ...

Likely to not be part of this:

• automatic architecture checks (note the list of possible tools that could be used in T286029)
• set up contract testing
  • create the initial api (empty) spec
• publish autodocs