feat(openapi): Add #[ApiResponse] annotation for declarative response descriptions

[usernane]

Problem Statement

Currently, to add response descriptions to the OpenAPI spec, you must call addResponse() programmatically in the constructor. There is no declarative annotation-based approach, which is inconsistent with the rest of the annotation-driven API design (#[GetMapping], #[RequestParam], #[ResponseBody], etc.).

Proposed Solution

Add a repeatable #[ApiResponse] attribute that can be placed on service methods:

#[GetMapping]
#[ResponseBody]
#[ApiResponse(status: '200', description: 'List of products or a single product')]
#[ApiResponse(status: '404', description: 'Product not found')]
public function getProducts(): array {
    // ...
}

Implementation:

1. Create WebFiori\Http\Annotations\ApiResponse:

#[Attribute(Attribute::TARGET_METHOD | Attribute::IS_REPEATABLE)]
class ApiResponse {
    public function __construct(
        public string $status = '200',
        public string $description = '',
    ) {}
}

2. In WebService::toPathItemObj(), read #[ApiResponse] attributes from the mapped method and build the ResponsesObj from them instead of the default "200" => "Successful operation" fallback.

3. If addResponse() was called programmatically, those take priority over annotations.

Alternatives Considered

• Using doc-block annotations (rejected — framework uses PHP 8 attributes exclusively)
• Class-level annotation (rejected — ambiguous for services with multiple HTTP methods)

Breaking Change

No

Additional Context

This came up while building the blog example for the OpenAPI/Swagger documentation post. The current workaround is calling addResponse() in the constructor, which works but breaks the declarative pattern.