Use destination-only rename scope for skipped CI jobs

[lamemustafa]

Root cause

Skipped-job scope evaluates both destination and previous rename paths while the workflow's changed-path input is destination-only.

Rectification

Use the workflow's destination-only rename scope for skipped-job validation, or share one explicit rename policy across both sides.

Regression check

python3 scripts/merge-gate.test.py

Scope

Deferred from PR #335 under the owner-approved P1-only merge stopping rule.

[lamemustafa]

Duplicate of #372. Verified: both target validate_skipped_ci_jobs() at the same awk line (~L797 of scripts/merge-gate.sh), describing the same defect — skipped-job scope includes rename source paths while the workflow's changed-path input is destination-only — with the same fix direction, phrased "use destination-only" here and "mirror the workflow's semantics" there.

Closing as duplicate; discussion continues on #372.