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/cache.py

@@ -0,0 +1,17 @@
+from django.core.cache import cache
+
+
+def get_redis_key(tenant_schema: str, module: str, key: str) -> str:
+    return f"{tenant_schema}:{module}:{key}"
+
+
+def cache_get(tenant_schema: str, module: str, key: str, default=None):
+    return cache.get(get_redis_key(tenant_schema, module, key), default)
+
+
+def cache_set(tenant_schema: str, module: str, key: str, value, timeout: int = 300) -> None:
+    cache.set(get_redis_key(tenant_schema, module, key), value, timeout)
+
+
+def cache_delete(tenant_schema: str, module: str, key: str) -> None:
+    cache.delete(get_redis_key(tenant_schema, module, key))