[REFACTOR] Desktop acceptance matrix and certification gates

[ksamaschke]

Scoped Behavior Slice

Improve structure, naming, and maintainability for 'Desktop acceptance matrix and certification gates' without changing externally verified behavior.

Test Command or Verification Path

• Re-run the scoped GREEN verification after cleanup.
• Run the relevant regression suite to confirm no behavior changed.

Required Evidence Format

• Link passing evidence back to the GREEN work-item.
• Capture passing regression or suite evidence after refactor cleanup.

Tracking

• Type: work-item
• Phase: refactor

Parent: #186

[ksamaschke]

Completed as part of merged story #186 in PR #198 (merge commit dbab09b, follow-up commit 523c6a6). The REFACTOR slice is reflected in the completed full desktop target matrix and the stabilized release validation path. Closing stale TDD child issue.