refactor(workflow): simplify edge configuration

backend/tests/test_pipeline_events.py

@@ -64,7 +64,7 @@ class _Brain:
 
     async def on_client_ready(self):
         for content, timestamp in (
-            ("Start Edge 过渡语", "2026-07-14T10:00:00.200+00:00"),
+            ("Message 节点播报", "2026-07-14T10:00:00.200+00:00"),
             ("Agent 固定进入语", "2026-07-14T10:00:00.300+00:00"),
         ):
             await self.worker.queue_frame(
@@ -118,7 +118,7 @@ class PipelineEventTest(unittest.IsolatedAsyncioTestCase):
         ordered = sorted(transcripts, key=lambda message: message["timestamp"])
         self.assertEqual(
             [message["content"] for message in ordered],
-            ["助手开场白", "Start Edge 过渡语", "Agent 固定进入语"],
+            ["助手开场白", "Message 节点播报", "Agent 固定进入语"],
         )
         self.assertEqual(transcripts[0]["timestamp"], greeting_time)
         self.assertEqual(brain.prepared_greeting, "助手开场白")