fix(types): resolve forward-reference return annotations via get_type_hints

[devteamaegis]

Summary

Closes #950

When a module uses from __future__ import annotations (PEP 563), all annotations are stored as lazy strings at runtime. inspect.signature().return_annotation therefore returns the raw string (e.g. 'Recipe') rather than the actual class. This meant PythonFunction.from_function stored 'Recipe' (a string) as return_annotation, which broke any downstream code that tried to construct a Pydantic schema from it.

Root cause: inspect.signature() preserves the string literal as-is under PEP 563. Only typing.get_type_hints() resolves the forward reference back to the real type.

Fix

In PythonFunction.from_function, replace:

"return_annotation": sig.return_annotation,

with a get_type_hints() call that resolves the annotation, falling back to sig.return_annotation if resolution fails (e.g. the type is not importable in the current scope):

try:
    hints = get_type_hints(func)
    resolved_return = hints.get("return", sig.return_annotation)
except Exception:
    resolved_return = sig.return_annotation

Tests

Two regression tests added in tests/basic/utilities/test_types.py::TestPythonFunctionFromFutureAnnotations:

• test_string_annotation_is_resolved_to_type — string annotation -> "Dish" must resolve to the Dish class
• test_non_string_annotation_still_works — normal -> list[Ingredient] must continue to work unchanged