fix: preserve takeover and share token integrity

digital-avatar-app/backend/tests/test_chat_orchestration.py

@@ -121,6 +121,12 @@ class ChatOrchestrationTests(unittest.TestCase):
         self.assertNotIn("config", payload)
         self.assertNotIn("ownerId", payload)
 
+    def test_unshared_avatars_do_not_reuse_a_unique_share_token(self):
+        first = Avatar(name="first")
+        second = Avatar(name="second")
+        self.assertIsNone(first.share_token)
+        self.assertIsNone(second.share_token)
+
     def test_standard_answer_can_be_emitted_as_sse_chunks(self):
         self.assertEqual(list(_iter_text_chunks("标准答案内容", size=2)), ["标准", "答案", "内容"])