Add support for parameter schemas in Path and add test

[Foorack]

Fixes #1324

When I add an enum only in the header, it gets referenced in the yaml output, but there is no corresponding schema in the yaml schema definitions. When I additionally add the enum to a body, it appears in the schema definitions and works as expected.

[Copilot]

Pull Request Overview

Adds support for including component schemas for path parameters (such as header enums) in generated OpenAPI docs and provides a test that validates an enum-only header parameter is added to components.schemas.

• Implements get_component_schemas on Parameter to extract schema references
• Integrates parameter schemas into the SchemaReferences implementation in path.rs
• Adds a test (derive_enum_header_parameter_includes_schema) reproducing #1324 and verifying the enum header appears in components.schemas

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
tests/path_parameter_derive_test.rs	New test ensuring header-only enum parameters generate schemas
src/path/parameter.rs	New get_component_schemas method and iterator for parameters
src/path.rs	Wire up parameter schemas in SchemaReferences generation