v0.5.0 — idempotent, swappable-user-model-safe 0001_initial

Changed

• 0001_initial is now idempotent and swappable-user-model safe.
  The migration builds its tables through the schema editor
  (create_model), guarded to run only when dynamic_columns_* are
  absent, instead of a plain CreateModel. Two payoffs:

  • Pre-existing schema no longer collides. Projects that predate
    the package extraction (notably BPP, whose in-tree dynamic_columns
    app created these tables years ago) can apply 0001_initial onto a
    database that already carries the tables — it detects them and
    no-ops. This makes the dedicated MIGRATION_MODULES override such
    projects used to ship unnecessary; they can drop it and consume the
    package's migrations directly.
  • Custom user models resolve correctly on a from-empty build. The
    user FK is materialised by the schema editor against
    settings.AUTH_USER_MODEL, so a fresh migrate (or
    migrate --create-db / baseline rebuild) on a project with a
    swapped user model points the FK at the right table instead of a
    hard-coded auth_user.

  The migration state is unchanged (a CreateModel pair plus the
  existing constraints, now under SeparateDatabaseAndState), so
  databases that already recorded 0001_initial as applied are
  unaffected and makemigrations detects no drift.