feat: include account info in balance response

apps/api/tests.py

@@ -180,6 +180,7 @@ class BalanceApiTests(TestCase):
             username=f"balance-user-{suffix}",
             email=f"balance-user-{suffix}@example.com",
             password="password",
+            first_name="主账号",
         )
         self.api_key, self.raw_key = ApiKey.create_for_user(self.user, name="balance")
         self.client = APIClient()
@@ -225,12 +226,24 @@ class BalanceApiTests(TestCase):
         self.assertEqual(response.data["user"], self.user.username)
         self.assertEqual(response.data["points_balance"], 100)
         self.assertEqual(response.data["points_balance"], ledger_sum)
+        self.assertEqual(
+            response.data["account"],
+            {
+                "username": self.user.username,
+                "display_name": "主账号",
+            },
+        )
+        self.assertNotIn("email", response.data["account"])
+        self.assertNotIn("id", response.data["account"])
 
     def test_balance_returns_zero_without_creating_missing_wallet(self):
         response = self.client.get(self.url, **self.auth_header())
 
         self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.data["user"], self.user.username)
         self.assertEqual(response.data["points_balance"], 0)
+        self.assertEqual(response.data["account"]["username"], self.user.username)
+        self.assertEqual(response.data["account"]["display_name"], "主账号")
         self.assertFalse(UserWallet.objects.filter(user=self.user).exists())
 
     def test_balance_does_not_accept_web_session_without_api_key(self):