Coordinate semantics for checked transformations

Stable import boundary for checked transform geometry and the independent rearrange, repeat, and reduce denotations.

The source and output grouping conventions follow einops v0.8.2, einops.einops._reconstruct_from_shape_uncached and einops.einops._apply_recipe, at commit 8e911db71f2e693a0c434b041180388c685ed06f.