Preserve and validate feature ordering during composition refactoring

[nradakovic]

What

Add focused validation to ensure that feature extraction and composition do not change feature ordering or the effective behavior of toolchain feature application.

The goal is to prevent regressions caused by the structural refactor itself.

Acceptance Criteria

• Validation exists for the ordering-sensitive parts of the explicit feature model.
• The refactor does not change effective behavior due to reordered feature application.
• Any intentionally changed ordering is documented and justified.
• Maintainers can detect ordering regressions introduced by future refactors.

How

• Identify ordering-sensitive features and feature bundles in the current implementation.
• Add targeted validation or assertions that exercise effective feature behavior.
• Compare pre-refactor and post-refactor behavior for representative scenarios.
• Document any ordering assumptions that the composition model depends on.