Testbed-calibration traps in small-scale emergence science: two pre-registered negatives

Code and result logs for two pre-registered emergence negatives and the calibration diagnostics that prevent them. Code is MIT; result logs CC-BY-4.0. Figure/manuscript sources not included; large standard datasets not bundled. v1.2 adds the gamma-difficulty ladder, detector validation on real induction emergences, and scan-statistics analysis code and logs reported in the submitted manuscript.