Contract-First Bayesian Workflows for Hierarchical Behavioural Data // Provides transparent, contract-first infrastructure for Bayesian analysis of repeated-measures and hierarchical behavioural data. It supports approved Bernoulli-logit and positive lognormal duration workflows with readiness audits, deterministic simulation, explicit preparation, inspectable priors, prior and posterior predictive checks, restricted optional fitting through 'brms' and 'rstan', sampling diagnostics, prior sensitivity, parameter recovery, and conservative reporting. Core contracts and prior checks remain backend-independent.