Why: The multi-instance acceptance test still created alice with a literal password; backend U3 replaced local password-bearing creation with trusted pending-account activation, so the first pin bump past U3 failed test-pg with RECOVERY_CONTRACT_REPLACED. The seam was left pending by the U3 task and this PR is the first to cross it. Evidence: Full TestTwoInstancesOverSharedPG passes against a disposable PostgreSQL 16 container (identity ensure -> bootstrap-admin -> pending create with activation key -> key redemption -> grant-setup password -> api key -> all cross-instance scenarios, 15s). Impact: Test-only bootstrap rewrite (deployment-level identity ensured once per pair, admin bootstrapped first, alice activated through the key redemption and grant-setup password flow); no product code changes. Refs: Dev task feature/pptx-gate-reference-integrity; backend U3 #198