Fix SuperAdmin logout loop (this-binding) + add Fix Grant button to restore revoked embed grants

Complete Stripe billing E2E: checkout, onboarding, auto catalog sync.

refactor: Phase 6A+6B — top-level imports and Pydantic schema upgrades

Refactor: complete 10/10 modularity — superadmin/routers/, core/startup/, pipeline/generation.py, slim main.py