This MR adds API docs generation based on @equinox 2dba85db. You may build docs locally with make api-docs, generated files are Swagger/ OpenAPI version 2 and can be found in api/docs.
When running the dev server, Swagger UI is available at /api/docs/index.html.
The API is not changed with this MR. Endpoints are just annotated with comments according to swaggo/swag documentation.
An OpenAPI 3 scheme is generated in CI with openapi-generator-cli. It is available as an artifact of the job build-openapi-3-scheme.