Routes each requested contrast row through the Rust fixed-effect inference
bridge and reports the upstream estimability assessment verbatim.
Returned rows carry status (the closed enum from upstream:
estimable, not_estimable, aliased, ...), a boolean estimable
convenience flag, the contrast rank and requested_rank, and a
stable reason populated only when the engine refuses the contrast.
Usage
estimability(fit, L = NULL, ...)
# S3 method for class 'mm_lmm'
estimability(fit, L = NULL, ...)