Implement base model class with serialization helpers

[codebestia]

All response models should share a common base that provides from_dict(data: dict), to_dict(), and a readable __repr__. Using Pydantic as the base eliminates boilerplate validation and gives free type coercion.

Proposed Steps:

• Create src/shade/models/__init__.py and src/shade/models/base.py.
• Define ShadeObject(pydantic.BaseModel) with model_config = ConfigDict(populate_by_name=True, extra="allow").
• Add to_dict() method wrapping model.model_dump().
• Add a classmethod from_dict(cls, data: dict) that constructs the model.
• Override __repr__ to show class name and primary ID field.

Acceptance Criteria:

• All models can be round-tripped through from_dict(m.to_dict()) without data loss.
• Unknown fields from the API are accepted without raising (extra="allow").
• repr(model) shows the class name and key ID field.
• Pydantic validation errors surface as InvalidRequestError, not raw ValidationError.

[KodeSage]

please assign this issue to me. I have experience designing Python SDKs with a strong focus on maintainability, type safety, and clean model abstractions. I've worked with Pydantic-based models, centralized validation, and reusable base classes that reduce duplication while keeping APIs intuitive and consistent.
For this issue, I would introduce a shared ShadeObject base model in src/shade/models/base.py and expose it through src/shade/models/init.py. The base class would use ConfigDict(populate_by_name=True, extra="allow") to support flexible API responses while preserving type validation. I'd implement from_dict() and to_dict() helpers to provide a consistent serialization interface, along with a custom repr that highlights the model's class name and primary identifier for easier debugging.

[grantfox-oss]

🦊 GrantFox — @KodeSage has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #36)
2. Your PR will be reviewed by the ShadeProtocol maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign | FWC26 campaign!

@KodeSage's PR #47 was approved and merged by @codebestia.

🏆 @KodeSage: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (242 total points). Track your full progress on GrantFox.

👏 Great work, @KodeSage! Keep contributing to ShadeProtocol.