Enhance `pydantic_to_click` decorator for CLI options

[ephur]

Refactor and expand pydantic_to_click to support:

• Enum and Literal fields as click.Choice
• include/exclude filtering of fields
• support for cli_name override in json_schema_extra
• normalize PydanticUndefined defaults
• optional CLI option doc generation from model metadata

[ephur]

🤖 Initial triage (AI-generated):

This enhancement targets your pydantic_to_click decorator. The architecture is already strong — this issue is about deepening flexibility:

⚙️ Additions include:

• Enum + Literal → click.Choice
• include / exclude fields to filter model fields per command
• Support cli_name override in json_schema_extra
• Auto-doc generator or option printer for help/markdown

🧪 Test with nested models and optional values to ensure robustness.

Disclaimer: This triage is AI-generated and may need refinement.