GeezerVison

The many-to-many branch of path2d computes weighted predecessors, then discards them and calls unweighted hillclimb2d. With cardinal cost 1 and diagonal cost 3, this can replace two cheap cardinal steps with an expensive diagonal.

Return pf.path_from(best_ij) after choosing the nearest start. Keep endpoint selection and unreachable handling. Equal-cost routes may choose different tied predecessors.

The regression covers four diagonal settings. An independent heap solver on the bundled sample dungeon confirms all 59 previously incorrect many-to-many queries, with all 1,680 single-endpoint path controls unchanged. A separate automatic-heuristic correction handles another 60 single-endpoint failures; composing both fixes matches all 2,240 queries.

Full headless tests pass (325 passed, 95 skipped), using the pinned resource submodule and SDL dummy audio driver. Mypy and applicable project formatting/hooks pass.