Add interop contract tests

[sebastianorbell-qm]

Summary

• add shared interop contract tests for library imports, QUA, QualibrationNode, and xarray
• keep node-specific interop tests for 18a_coupler_zero_coarse run_action contracts

Process

• Review after merging Testing infrastructure and CI tiers #56 and Add unit tests for coupler zero point #57

Testing

• uv run pytest -m interop --tb=line -q
• uv run pre-commit run --files tests/interop/test_library_contracts.py tests/interop/test_qualibration_node_contracts.py tests/interop/test_qua_contracts.py tests/interop/test_xarray_contracts.py tests/interop/calibrations/CZ_calibration_fixed_couplers/test_18a_coupler_zero_coarse_interop.py