CI statistic conformance

Suite path: conformance/discovery/ci_stats

GPDC / CMIknn / G² statistic and p-value pins. Oracle regeneration: see expected.json → reference.command (out-of-repo).

Expected summary

Top-level keys: atol_p, atol_stat, generation, gpdc_atol_stat, gpdc_rtol_stat, n, reference, rtol_p, rtol_stat, seed, tolerance_class (11 fields).