Create a Linux-specific feature composition layer #86

What

Introduce a QNX-specific feature composition layer that assembles all QNX-only required explicit features on top of the shared feature module.

The goal is to preserve QNX-specific behavior while reducing duplication and improving maintainability.

Acceptance Criteria (DoD)

• QNX-only required features are assembled from a dedicated QNX-specific composition layer.
• The QNX toolchain template becomes thinner and no longer owns duplicated shared feature logic.
• QNX behavior remains unchanged for supported scenarios after the refactor.
• Ownership of QNX-specific features is clear and separated from shared/common features.

How

• Identify QNX-specific required features from the classification task.
• Create a QNX-focused module or feature bundle function that returns those features.
• Update the QNX toolchain assembly to consume shared features plus QNX-specific features.
• Validate that existing supported QNX toolchain behaviors continue to work.