Shift Analysis DTO
@Serializable
Wire-safe, complete left-shift analysis for a continuous fit — the full content of the standard report's "Shift Parameter Analysis" section. Carries the estimated left shift, whether the data has zeros/negatives, the zero tolerance used, and the bootstrap confidence interval for the data minimum that drives the shift recommendation.
The CI for the minimum is a bootstrap estimate computed at fit time; a live canonical render recomputes it (and may differ slightly because bootstrap resampling is stochastic). Discrete fits do not shift, so this is null on the discrete path.