Map a row-major MatrixData into the feature-name → value objects the
sidecar /predict expects, in the model's FROZEN feature-schema order. Columns
present in the matrix but not in the schema are dropped; schema columns missing
from the matrix are emitted as null (the sidecar imputes via fitted params).
Map a row-major MatrixData into the feature-name → value objects the sidecar
/predictexpects, in the model's FROZEN feature-schema order. Columns present in the matrix but not in the schema are dropped; schema columns missing from the matrix are emitted asnull(the sidecar imputes via fitted params).