Fix QuamRoot.load() NameError with TYPE_CHECKING forward references

[nulinspiratie]

Root cause

When a quam_dataclass component class uses from __future__ import annotations together with TYPE_CHECKING-only imports to avoid circular dependencies, QuamRoot.load() raises a NameError:

# qubit.py
from __future__ import annotations
from typing import TYPE_CHECKING
from quam.core import QuamComponent, quam_dataclass

if TYPE_CHECKING:
    from resonator import Resonator  # only imported by the type-checker, not at runtime

@quam_dataclass
class Qubit(QuamComponent):
    resonator: Resonator  # stored as the string "Resonator" at runtime

During loading, instantiate_quam_class(Qubit, ...) calls get_dataclass_attr_annotations(Qubit), which calls typing.get_type_hints(Qubit). That function tries to resolve the string annotation "Resonator" against qubit.py's global namespace — but since the import only happened under TYPE_CHECKING, Resonator is absent at runtime and a NameError is raised.

Saving (to_dict()) already worked because it never needs to resolve annotations.

How it's fixed

The fix introduces a fallback path in get_dataclass_attr_annotations() (quam/utils/dataclass.py):

get_type_hints(cls)
  → succeeds   → use as before (no change for existing code)
  → NameError  → _get_type_hints_with_fallback(cls)
                   collect raw __annotations__ from full MRO
                   eval each annotation string against the module's globals
                   substitute typing.Any for any that still can't be resolved

The key insight is that every serialised QuAM object already carries a __class__ key in its dict representation. instantiate_attrs() already reads that key to look up the concrete class via get_class_from_path() — completely independently of the annotation. So substituting Any for an unresolvable annotation is safe: the concrete type is recovered from __class__ at runtime instead.

The same NameError guard is added to _get_value_annotation() in quam_classes.py (returns None, meaning no element-type annotation for QuamDict/QuamList — already the safe default).

Changes

• quam/utils/dataclass.py: add _get_type_hints_with_fallback(), catch NameError in get_dataclass_attr_annotations()
• quam/core/quam_classes.py: catch NameError in _get_value_annotation()
• quam/components/helper_files/: Qubit and Resonator test fixtures with circular TYPE_CHECKING imports
• tests/serialisation/test_forward_references.py: 6 TDD tests covering save, load, and full roundtrip
• pyproject.toml: add [tool.pytest.ini_options] pythonpath = ["."] so the local source tree is used during test runs
• CHANGELOG.md: entry under ### Fixed

Test plan

• TestForwardRefSaving — to_dict() works and produces correct __class__ keys (baseline, was already passing)
• TestForwardRefLoading — Root.load(d) instantiates the correct component types and preserves reference strings
• TestForwardRefRoundtrip — save → load produces identical instances and identical dicts
• Full test suite: 633 passed, 0 failures

Closes #90

[nulinspiratie]

@JacobHast could you verify whether this resolves your circular naming issue?