ci: classify mux/ as macOS-neutral so mux-only PRs pass the routing guard - #7622

Bugbot Analysis Progress (51s elapsed)

✅ Gathered PR context (6s)
✅ Completed bug detection (44s)
✅ Posted analysis results (1s)

Final Result: Bugbot completed review - no issues found! ✅

Request ID: serverGenReqId_128d5e7b-5136-4ff9-8387-714f22485cb0