ci / vet-and-test (pull_request) Successful in 48s
Why: Since the system-managed settings change (#188), runtime.* writes at the user scope are rejected, so the mock startup flag failed with "system-managed settings require admin" and the serve process never became healthy - the Dev multi-instance integration regression. Evidence: go build ok; internal/app and internal/settings suites green (SELF); the Dev composite CI on the follow-up PR re-runs make test-multi-instance against this fix (GATE). Impact: The mock startup flag now seeds runtime.mock via MergeSystem (trusted operator input, effective for every tenant through the Effective merge chain); no HTTP surface changes. Refs: Dev PR #508; backend #188.