cmrdesign - Conditional Minimax Regret Design Rules

Implements Conditional Minimax Regret design rules for pilot-informed experimental assignment, as proposed in Yamin (2026) <doi:10.48550/arXiv.2607.16982>. Includes two-arm, unbounded two-arm, multi-arm, stratified, multiple-outcome, proxy-outcome, and pilot-planning tools. Variance bounds include Maurer and Pontil (2009) <doi:10.48550/arXiv.0907.3740> empirical-Bernstein bounds and exact Bernoulli confidence bounds.