[kostiushkin]

Summary

• Merge master (1.0.0) into openapi and finish the OpenAPI scaffold.
• Export: liver path schemas → OpenAPI 3 documents (generate / generate_schema), OTP json instead of jsx, LIVR + erlang_standard rule mapping.
• Import: OpenAPI Schema Object → erlang_standard field schema (from_openapi_schema) for liver:validate/2.
• Docs (doc/openapi.md, README, CHANGELOG) and CT suite openapi_schema_SUITE.

Scope / limitations

MVP only: no $ref / allOf / oneOf / document-level paths&methods; nullable ignored; single-sided min/max skipped. Unsupported constructs return {error, {unsupported, Reason}}.

Test plan

• make app
• make tests (including openapi_schema_SUITE: export LIVR + standard, import ok/error, unsupported $ref)
• Smoke: generate_schema/2 with output => json and decode with json:decode/1
• Smoke: from_openapi_schema/1 on a small object schema, then liver:validate/2

[coveralls]

coverage: 84.064% (-11.3%) from 95.333% — openapi into master