Promote ConfigColl exactness with MATLAB fixtures

[iahncajigas]

Summary

• promote ConfigColl to fixture-backed exact parity
• add MATLAB-backed fixture coverage for ConfigColl constructor and error branches
• refresh exactness audits and fixture consumers for related Trial/Events/ConfidenceInterval surfaces

Verification

• pytest -q tests/test_class_fidelity_audit.py tests/test_parity_manifest.py tests/test_parity_report.py tests/test_matlab_gold_fixtures.py tests/test_trial_fidelity.py tests/test_workflow_fidelity.py tests/test_trial_plotting_surface.py