chore: consolidate check helpers into resources/_check_helpers

[henchaves]

Summary

Consolidates the request-side check helpers that were spread between types/check.py and resources/evaluations/evaluations.py into a single shared resources/_check_helpers.py module. Merges the two list-builders into one parametrized function. No behavior change.

What changed

• New resources/_check_helpers.py housing IDENTIFIER_TO_KIND, check_param_to_spec, and check_params_to_specs(..., flat: bool).
• _check_params_to_api (test-cases shape) and _check_params_to_flat_specs (run-single shape) merged into check_params_to_specs(..., flat=False/True).
• Underscore prefixes dropped on the exported names — they're shared across sister modules inside a package-private file, matching the convention in resources/_included.py. Removes a # pyright: ignore workaround.
• _extract_check_params stays in types/check.py — response-side helper used by the Check / CheckConfig pydantic validators.
• Tests/imports updated accordingly.

[gemini-code-assist]

Code Review

This pull request centralizes the logic for converting check parameters into the wire format by introducing a new helper module, _check_helpers.py. It replaces several redundant internal implementations across the checks, evaluations, and test_cases resources and updates the corresponding tests. A bug was identified in the check_params_to_specs function where the flat=True branch fails to handle Pydantic models, which would lead to an AttributeError at runtime.

[gemini-code-assist]

The flat=True branch currently assumes params is a dictionary and calls .items(). However, params can also be a Pydantic BaseModel (as handled in check_param_to_spec). This will cause an AttributeError at runtime if a model is passed. Reusing check_param_to_spec ensures consistent handling of both dictionaries and models while also correctly stripping the type key.

Suggested change

	result.append({"identifier": identifier, **{k: v for k, v in params.items() if k != "type"}})
	else:
	entry: Dict[str, Any] = {"identifier": identifier, "enabled": check.get("enabled", True)}
	if params:
	entry["spec"] = check_param_to_spec(identifier, params)
	result.append(entry)
	if flat:
	spec = check_param_to_spec(identifier, params)
	spec.pop("kind", None)
	result.append({"identifier": identifier, **spec})
	else:
	entry: Dict[str, Any] = {"identifier": identifier, "enabled": check.get("enabled", True)}
	if params:
	entry["spec"] = check_param_to_spec(identifier, params)
	result.append(entry)