The `deprecated` field from OpenAPI operations is parsed but not exposed to templates

Describe the bug

The deprecated field on OpenAPI operation objects is parsed into the Operation schema model (operation.py#L31), but it is never carried over to the Endpoint dataclass that is passed to Jinja templates (openapi.py#L132-L152).

This means there is no way to check endpoint.deprecated in a custom template to conditionally emit deprecation warnings, docstring annotations, or @deprecated decorators.

The Endpoint dataclass is missing a deprecated: bool field, and the constructor at openapi.py#L419-L427 does not pass data.deprecated through.

Expected behavior

The Endpoint dataclass should include a deprecated: bool = False field, populated from data.deprecated during construction, so that templates can use {% if endpoint.deprecated %} to customize output for deprecated operations.

OpenAPI Spec File

Any spec with a deprecated operation, for example:

paths:
  /example:
    get:
      operationId: getExample
      deprecated: true
      responses:
        '200':
          description: OK

Desktop (please complete the following information):

• OS: macOS 26.3
• Python Version: 3.9.6
• openapi-python-client version: 0.28.2

从 openapi_python_client/schema/openapi_schema_pydantic/operation.py 中的 Operation 模型，以及 openapi_python_client/parser/openapi.py 中的 Endpoint 数据类和构造函数开始。跟踪 operation 数据如何到达传递给 Jinja 模板的 Endpoint，然后验证 deprecated operation 会公开 endpoint.deprecated，并且在未指定时默认为 false。