Tour Progress

Runtime **state** of an in-admin guided tour, one per (user, tour). Tour *definitions* live in code (``onboarding/tours/``); this model only records where a user is. It keys on the tour ``slug`` + ``version`` and a **stable step key** (never a positional index), so editing or reordering a tour never mis-points an in-progress user — a mismatch simply restarts the tour. See ``onboarding/tours/README.md``. Isolation: inherits ``SofisisAbstract.objects`` (``UserDbFilterManager``), which scopes every query by ``id_user_isis`` so a tenant never sees another tenant's progress.