qtbi 0.1.2

• Initial CRAN release.
• estimate_qtbi() encodes multi-exposure panels into a fixed Quantum Toxic Burden Index using within-cohort percentiles and a configurable synergy parameter.
• Optional potency-weighted readout via reference_doses, with automatic derivation and rescaling of weights through potency_weights_from_reference_doses() and normalize_potency_weights().
• diagnose_qtbi() provides synergy sensitivity and monotonicity diagnostics.
• Classical statevector simulation only; no quantum hardware or heavy visualization dependencies.