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

apps/org/models/org_unit.py

@@ -0,0 +1,57 @@
+from django.db import models
+
+from core.enums import OrgUnitAttribute, OrgUnitType
+from core.models.base import SoftDeleteModel
+
+
+class OrgUnit(SoftDeleteModel):
+    name = models.CharField(max_length=100)
+    type = models.CharField(max_length=20, choices=OrgUnitType.choices)
+    parent = models.ForeignKey(
+        "self",
+        null=True,
+        blank=True,
+        on_delete=models.RESTRICT,
+        related_name="children",
+        db_index=True,
+    )
+    path = models.TextField(
+        help_text="Materialized path: /root_id/.../self_id/ for subtree queries.",
+    )
+    depth = models.SmallIntegerField(default=0)
+    sort_order = models.IntegerField(default=0)
+    attribute = models.CharField(
+        max_length=10,
+        choices=OrgUnitAttribute.choices,
+        null=True,
+        blank=True,
+    )
+    address_city = models.CharField(max_length=50, blank=True, default="")
+    address_district = models.CharField(max_length=50, blank=True, default="")
+    address_detail = models.CharField(max_length=200, blank=True, default="")
+    latitude = models.DecimalField(max_digits=10, decimal_places=7, null=True, blank=True)
+    longitude = models.DecimalField(max_digits=10, decimal_places=7, null=True, blank=True)
+    manager = models.ForeignKey(
+        "org.Staff",
+        null=True,
+        blank=True,
+        on_delete=models.SET_NULL,
+        related_name="managed_org_units",
+    )
+    established_at = models.DateField(null=True, blank=True)
+    phone = models.CharField(max_length=30, blank=True, default="")
+    ext_start = models.IntegerField(null=True, blank=True)
+    ext_end = models.IntegerField(null=True, blank=True)
+    is_active = models.BooleanField(default=True)
+
+    class Meta:
+        db_table = "org_units"
+        indexes = [
+            models.Index(fields=["parent"], name="idx_org_units_parent"),
+            models.Index(fields=["type"], name="idx_org_units_type"),
+            models.Index(fields=["path"], name="idx_org_units_path"),
+        ]
+        ordering = ["sort_order", "name"]
+
+    def __str__(self) -> str:
+        return f"{self.name} ({self.type})"