MCS - prep for labeled/unlabeled graph problem types

[scal444]

No description provided.

[greptile-apps]

Greptile Summary

The PR introduces labeled and unlabeled fMCS compatibility policies.

• Adds deterministic bond enumeration and atom/bond match-table construction.
• Adds a labeled graph data structure with vertex and edge labels.
• Adds policy unit tests and registers them with CMake.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
src/mcs/fmcs_cuda/fmcs_policy.cuh	Adds unlabeled and exact-label fMCS policies; the bounds-checked edge-label lookup resolves the previously reported unchecked access.
src/mcs/labeled_graph.h	Adds the graph, vertex-label, and edge-label container used by the labeled policy.
tests/test_fmcs_policy.cpp	Covers bond enumeration, compatibility tables, missing and undersized labels, and disabled label matching.
tests/CMakeLists.txt	Builds and registers the new fMCS policy test executable.

_{Reviews (3): Last reviewed commit: "Merge branch 'main' into mcs-split-04-po..." | Re-trigger Greptile}

[scal444]

Towards #221

[evasnow1992]

Thank you! LGTM.