feat: scaffold Django multi-tenant project with 5 of 9 apps

Phase 1 scaffolding: config/, core/, base models, AES-256-GCM phone encryption, enums mirror

apps.tenant: Tenant + Domain (django-tenants)

apps.org: 11 models (OrgUnit hierarchy, Staff, audit logs)

apps.account: 4 models (UserAccount as AUTH_USER_MODEL, login/password tracking)

apps.permission: 7 models (RBAC + overrides + datascope + append-only changelog)

apps.region: 5 models (District, BusinessArea, MetroLine, MetroStation, School)

All migrations generated, manage.py check passes

core/models/__init__.py

@@ -0,0 +1,15 @@
+from core.models.base import (
+    ActiveManager,
+    AuditedModel,
+    SoftDeleteModel,
+    TimeStampedModel,
+    UUIDPrimaryKeyModel,
+)
+
+__all__ = [
+    "ActiveManager",
+    "AuditedModel",
+    "SoftDeleteModel",
+    "TimeStampedModel",
+    "UUIDPrimaryKeyModel",
+]