Function run_uncertainty_truing_v1 

pub fn run_uncertainty_truing_v1(
    request: &UncertaintyTruingRequestV1,
) -> Result<UncertaintyTruingReportV1, UncertaintyTruingErrorV1>

Run the opt-in uncertainty-aware joint MV+BC truing path.

Observation sigmas are absolute and known. Consequently posterior covariance is the inverse likelihood-plus-prior information matrix and is not rescaled by residual RMS. No identifiability heuristic changes the requested two-parameter fit; weak or collinear data instead produce broad uncertainty, warnings, or a structured approximation failure.