Server-Side Treatment Effect Computation for Federated Studies

Server-side 'DataSHIELD' package that computes local average treatment effect (ATE) statistics from arm-specific regression coefficients provided by the analyst. Implements the server-side component of the G-formula estimator from 'Federated Causal Inference: Multi-Study ATE Estimation beyond Meta-Analysis' (R. Khellaf, A. Bellet and J. Josse, 2025), enforcing 'DataSHIELD' disclosure controls throughout.