feat: add governance bootstrap models

backend/apps/accounts/models.py

@@ -1 +1,44 @@
-# Use Django's built-in User, Group, and Permission models for MVP RBAC.
+from django.conf import settings
+from django.db import models
+
+
+class UserGroup(models.Model):
+    name = models.CharField(max_length=120, unique=True)
+    code = models.CharField(max_length=80, unique=True)
+    description = models.TextField(blank=True)
+    users = models.ManyToManyField(settings.AUTH_USER_MODEL, blank=True, related_name="business_groups")
+    is_active = models.BooleanField(default=True)
+    created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)
+
+    class Meta:
+        ordering = ["name"]
+
+    def __str__(self) -> str:
+        return self.name
+
+
+class MenuItem(models.Model):
+    code = models.CharField(max_length=120, unique=True)
+    title = models.CharField(max_length=120)
+    path = models.CharField(max_length=200, blank=True)
+    icon = models.CharField(max_length=80, blank=True)
+    parent = models.ForeignKey(
+        "self",
+        null=True,
+        blank=True,
+        on_delete=models.CASCADE,
+        related_name="children",
+    )
+    sort_order = models.PositiveIntegerField(default=0)
+    permission_code = models.CharField(max_length=120, blank=True)
+    is_visible = models.BooleanField(default=True)
+    is_enabled = models.BooleanField(default=True)
+    created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)
+
+    class Meta:
+        ordering = ["sort_order", "id"]
+
+    def __str__(self) -> str:
+        return self.title