Add OpenAPI spec with Swagger UI to API reference

[gaarutyunov]

Description

Add interactive OpenAPI documentation to the API reference page using Swagger UI. This replaces the manual markdown endpoint documentation with a machine-readable OpenAPI 3.0 specification rendered via the mkdocs-swagger-ui-tag plugin.

Changes include:

• docs/reference/openapi.yaml - Complete OpenAPI 3.0 spec covering all REST API endpoints
• docs/reference/api.md - Updated to embed Swagger UI widget
• docs/assets/swagger-hide-models.css - CSS to hide redundant info header in Swagger UI
• mkdocs.yml - Added swagger-ui-tag plugin configuration
• requirements.txt - Added mkdocs-swagger-ui-tag dependency

Motivation and Context

The current API documentation is manually maintained in markdown, which can become outdated and doesn't provide interactive features. An OpenAPI spec enables:

• Interactive "Try it out" functionality

• Auto-generated client SDKs

• Better schema documentation

• Easier maintenance

• I have raised an issue to propose this change (required)

How Has This Been Tested?

Tested locally using mkdocs serve - verified Swagger UI renders correctly and all endpoints are documented.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have signed-off my commits with git commit -s

[alexellis]

Hey @gaarutyunov just saw this.. we'll have a look at it soon. We also generated openapi definitions recently after some changes and additional endpoints.

Alex