[chore] pydantic validation for scheduler and structured outputs configs

[AlpinDale]

No description provided.

[gemini-code-assist]

Code Review

This pull request refactors the configuration classes for the scheduler and structured outputs to use pydantic's validation features more idiomatically. The changes replace manual validation in __post_init__ or model validators with pydantic.Field constraints and field_validator. This generally improves code clarity and correctness. However, I've identified one potential issue where moving validation from a model_validator to Field validators changes the validation timing, potentially leaving values modified in __post_init__ unvalidated. This could lead to issues in the future.