feat: RBAC Phase 1 — consolidate user roles into 4-value enum

Consolidate User.role (2-value: admin/store) + User.is_super_admin (boolean)
into a single 4-value UserRole enum: super_admin, platform_admin,
merchant_owner, store_member. Drop stale StoreUser.user_type column.
Fix role="user" bug in merchant creation.

Key changes:
- Expand UserRole enum from 2 to 4 values with computed properties
  (is_admin, is_super_admin, is_platform_admin, is_merchant_owner, is_store_user)
- Add Alembic migration (tenancy_003) for data migration + column drops
- Remove is_super_admin from JWT token payload
- Update all auth dependencies, services, routes, templates, JS, and tests
- Update all RBAC documentation

66 files changed, 1219 unit tests passing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/modules/tenancy/models/__init__.py

@@ -33,7 +33,7 @@ from app.modules.tenancy.models.merchant import Merchant
 from app.modules.tenancy.models.merchant_domain import MerchantDomain
 from app.modules.tenancy.models.platform import Platform
 from app.modules.tenancy.models.platform_module import PlatformModule
-from app.modules.tenancy.models.store import Role, Store, StoreUser, StoreUserType
+from app.modules.tenancy.models.store import Role, Store, StoreUser
 from app.modules.tenancy.models.store_domain import StoreDomain
 from app.modules.tenancy.models.store_platform import StorePlatform
 from app.modules.tenancy.models.user import User, UserRole
@@ -62,7 +62,6 @@ __all__ = [
     # Store
     "Store",
     "StoreUser",
-    "StoreUserType",
     "Role",
     # Merchant configuration
     "MerchantDomain",