Plan + both READMEs updated for the Authentik Authorization-Code + PKCE
flow, the Leitungsteam admin screen, the widened LT-admin guards, the
issuer trailing-slash normalisation, and the backend now serving the
Flutter web build (SPA fallback for /v1/auth/callback). Verification
section records the local-Postgres E2E for LT admin + onboarding approval,
and notes the OIDC browser round-trip still needs a test account.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>