Integrate compiler warning features into `reference_integration`

[nradakovic]

What

Confirm that the warning features can be consumed correctly in a representative downstream integration.

Acceptance Criteria (DoD)

• reference_integration consumes the new compiler warning features from score_cpp_policies.
• The integration builds and uses the warning feature model as intended.
• Any required adjustments for downstream consumption are identified and tracked.
• reference_integration serves as a validation reference for follow-up adopters.

How

• Add compiler warning feature integration to reference_integration.
• Update the integration to consume the new warning policy from score_cpp_policies.
• Verify that the integration behaves as intended with the migrated feature model.
• Use the integration outcome to identify adoption gaps before broader rollout.