fix(HEL-494): 数据中枢独占调度，主网站不再回退旧接口

主网站只向中枢要业务数据；来源选择、切源、补数全部在中枢内部完成，失败不再走东财/腾讯/Tushare 保底。

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: multica-agent <github@multica.ai>

tests/test_chart_data_provider.py

@@ -202,7 +202,7 @@ class DatahubChartFallbackTests(unittest.TestCase):
         self.assertEqual(hub.calls, ["601318"])
         self.assertEqual(fallback.requests, [])
 
-    def test_datahub_timeout_or_empty_falls_back_to_eastmoney(self):
+    def test_datahub_timeout_or_empty_does_not_use_old_channel(self):
         fallback = LookbackChartClient()
         for hub in (
             FakeHub(chart=None),
@@ -213,10 +213,9 @@ class DatahubChartFallbackTests(unittest.TestCase):
             EastmoneyChartClient._cache.clear()
             fallback.requests.clear()
             client = MarketChartClient(IfindHttpClient(), fallback, hub)
-            payload = client.stock_intraday("000001")
-            self.assertEqual(payload["trade_date"], "2026-09-07")
-            self.assertGreaterEqual(len(payload["points"]), 1)
-            self.assertTrue(fallback.requests)
+            with self.assertRaises(ChartDataError):
+                client.stock_intraday("000001")
+            self.assertEqual(fallback.requests, [])
 
     def test_datahub_daily_skips_ifind(self):
         hub = FakeHub(