Merged — validated together with a batch of related RaviTharuma PRs in one combined worktree (typecheck:core clean, complexity/file-size/changelog gates green, focused tests passing). Thanks for the contribution!
Integrated into release/v3.8.8. Applied review fixes: moved the SELECT 1 into a pingDb() db helper (no raw SQL in route, Hard Rule #5) + the 503 catch no longer leaks err.message (Hard Rule #12). Thanks @herjarsa!