Phase 3b of migration #2: Middleware.spec.basicAuth.secret now references the
Infisical-managed secret. Secret stanza in auth.yaml left in place as fallback
until 3b is verified (401 w/o creds, 200 w/ creds), then removed in 3c.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>