Returns the (currently intercept-only) component formulas plus the
random-effect specification preserved at fit time. Hurdle does not yet
support factor or covariate effects on its Part I (logit participation)
or Part II (log-consumption intensity) components; both binary and
consumption are ~ 1. The API is intentionally aligned with
formula.beezdemand_tmb() so the shape extends without breaking when
hurdle components gain factor/covariate support.
Usage
# S3 method for class 'beezdemand_hurdle'
formula(x, ...)