feat(HEL-490): 剩余行情改由数据中枢主线路提供

正式页面以 8766 为主线路，旧接口只作故障备用；compose 钉死全部 DATAHUB_READ_*，避免现网残留 0 造成假完成。

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

backend/data/gateway.py

@@ -47,6 +47,31 @@ class DataGateway:
     def batches(self, trade_date: str, dataset: str = "") -> list[dict[str, Any]] | None:
         return self.datahub.batches(trade_date, dataset)
 
+    def datahub_status(self) -> dict[str, Any]:
+        from backend.data.datahub.route_state import DATASET_LABELS, LEDGER
+        from backend.data.datahub.settings import DATASETS
+
+        settings = self.datahub.settings
+        flags = []
+        enabled = 0
+        for name in DATASETS:
+            read = bool(settings.flags(name).read)
+            if read:
+                enabled += 1
+            flags.append({"dataset": name, "label": DATASET_LABELS.get(name, name), "read": read})
+        routes = LEDGER.snapshot()
+        fallbacks = [item for item in routes if item.get("route") == "legacy"]
+        return {
+            "configured": bool(settings.token and settings.base_url),
+            "base_url": settings.base_url,
+            "enabled_reads": enabled,
+            "total_reads": len(DATASETS),
+            "flags": flags,
+            "routes": routes,
+            "fallback_count": len(fallbacks),
+            "fallback_labels": [str(item.get("label") or item.get("dataset")) for item in fallbacks],
+        }
+
     def assert_source(self, dataset_id: str, provider_id: str, usage: DataUsage) -> None:
         self.policy.assert_allowed(dataset_id, provider_id, usage)