isSetupLocked() now checks for an unclaimed local wizard user
(oidcIss IS NULL, claimed=false) before firing the effective-config
branch. During the credential→complete window, this sentinel prevents
a production container with VAPID env set from blocking POST /complete
with 423. The explicit setup_complete flag (Check 1) still locks
unconditionally once written. Adds regression test that sets VAPID env
explicitly (no beforeEach clearing) to reproduce the production scenario.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>