Unexecuted graph and classical benchmark checks

The code below uses only the Python standard library. It checks a declared finite graph for acyclicity, late-query reachability, and bypass paths after inserting explicit cut-port proxy vertices.

It does not check physical completeness, random-input independence, apparatus dimensions, or quantum correlations. The exact classical enumeration is a separate check of the $256$ deterministic two-state encoding–decoding table pairs.