feat(phase12): RetentionCurveSimulator, R10, 150-sample dataset, model trained, 14 tests PASS, gate PASS

phase 11 passed

feat(phase10): ABScriptEnv, ContrastiveReward, A/B rollout fn, 25 tests PASS, gate PASS

feat(phase9): platform reward divergence — PlatformRegistry, R9 PlatformPacing, R1/R2 platform-aware, 20 tests PASS, gate PASS

Phase 7 implemented

Phase 5 implemented