Workbook Change Assurance Benchmark 0.10.0

Precision as displayed, made reviewable

This release adds governance.precision_as_displayed_enabled: a workbook pair whose stored 10.005 input, two-decimal format, formulas, and local downstream reference remain unchanged while calcPr/@fullPrecision moves from true to false.

The fixture records a stored calculation control only. It does not open or save an Excel workbook, calculate a formula, claim a rounded stored value, or claim that any client applies the setting.

The optional FormulaFence adapter requires the exact isolated FF009 full-precision transition with every other stored calculation control unchanged.

Validation: 25 cases, 27 declared facts, 49 tests under Python 3.12 and 3.13, clean Python 3.12 wheel installation, and hosted CI under Python 3.10 and 3.13.