feat: support OpenAPI 3.2 additional operations

[cmmoran]

Summary

Add OpenAPI 3.2 Path Item additionalOperations support to RapiDoc, including custom HTTP methods and request-body-aware operation handling.

Why

RapiDoc currently discovers and renders only the fixed operation keys. OpenAPI 3.2 permits additional operation keys, so valid operations can be omitted or rendered with incorrect method behavior.

Implementation

• Preserve custom method names while parsing operation data.
• Render custom methods consistently with standard methods.
• Add query/custom-method styling and associated source support.
• Keep generated dist/ and documentation bundles out of the PR per CONTRIBUTING.md.

Reference: OpenAPI 3.2 Path Item Object. No new RapiDoc attribute, method, or event is introduced.

Validation

• yarn build via Yarn 1.22.22 completed successfully.
• The build emitted three existing webpack asset-size performance warnings; no compilation errors occurred.
• Generated build output was restored and is not included in the PR.