fix: sdk label aliases

[kenwoodjw]

Pull Request Checklist

Fixes ##345
Thank you for your contribution! Before submitting your PR, please make sure you have completed the following checks:

Compatibility Check

• I have checked whether this change affects the backward compatibility of the plugin declared in README.md
• I have checked whether this change affects the forward compatibility of the plugin declared in README.md
• If this change introduces a breaking change, I have discussed it with the project maintainer and specified the release version in the README.md
• I have described the compatibility impact and the corresponding version number in the PR description
• I have checked whether the plugin version is updated in the README.md

Available Checks

• just build has passed
• Relevant documentation has been updated (if necessary)

[gemini-code-assist]

Code Review

This pull request refactors the I18nObject model to use standard camelCase/PascalCase-like attributes (en_US, zh_Hans, pt_BR, ja_JP) instead of lowercase ones, updating all references across the codebase and adding corresponding unit tests. A high-severity issue was identified in FormOption where overriding __init__ to set a default label fails under Pydantic v2 because validation occurs before the fallback logic is executed; using a @model_validator(mode="before") is recommended instead.

[gemini-code-assist]

In Pydantic v2, overriding __init__ to set default values for required fields (like label) does not work as expected. When super().__init__(**data) is called, Pydantic immediately validates the input data. If label is missing from data, a ValidationError is raised before the fallback logic if not self.label: can ever be reached. Conversely, if label is provided, self.label is already populated, making the fallback block dead code.\n\nTo fix this, we should use a @model_validator(mode="before") classmethod, similar to how it is done in ProviderModel and ParameterRule. This allows us to inject the fallback label into the input dictionary before Pydantic performs field validation.

    @model_validator(mode="before")\n    @classmethod\n    def validate_label(cls, data: dict) -> dict:\n        if isinstance(data, dict) and "value" in data and not data.get("label"):\n            data["label"] = I18nObject(en_US=str(data["value"]))\n        return data

[kenwoodjw]

Please review again

[kenwoodjw]

@fatelei @crazywoola Please help review this PR.