MCS - prep for labeled/unlabeled graph problem types

[scal444]

No description provided.

[greptile-apps]

Greptile Summary

Adds labeled and unlabeled fMCS compatibility policies.

• Introduces LabeledGraph with vertex and edge labels.
• Builds atom and bond match tables with optional exact label matching.
• Safely treats absent or undersized label storage as zero-valued labels.
• Adds policy tests and registers the new test executable.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains; the bounds-checked edge-label lookup and regression tests address the prior unchecked-access finding.

Important Files Changed

Filename	Overview
src/mcs/fmcs_cuda/fmcs_policy.cuh	Adds compatibility-table policies, deterministic bond enumeration, and bounds-checked edge-label lookup that resolves the previously reported unchecked access.
src/mcs/labeled_graph.h	Defines the labeled graph container used by the new policy.
tests/test_fmcs_policy.cpp	Covers labeled and unlabeled matching, deterministic bond ordering, disabled label matching, and missing or undersized label arrays.
tests/CMakeLists.txt	Registers and links the new fMCS policy test target.

_{Reviews (2): Last reviewed commit: "Guard missing fMCS edge labels" | Re-trigger Greptile}

[scal444]

Towards #221