Communication-Efficient Varying Coefficient Mixed-Effects Models // Scalable inference for Varying Coefficient Mixed-Effects Models (VCMMs) with large, correlated random effects. Implements sufficient-statistics, one-step communication- efficient surrogate likelihood, and SVD-stabilized (Singular Value Decomposition) estimators with Kronecker and separable covariance structures. Implements the methodology of Jalili and Lin (2025) doi:10.48550/arXiv.2511.12732.