feat(HEL-402): 接通网站首批只读 datahub 并建立双路对比

默认全部读取/影子开关关闭，网站继续走旧 Tushare 链路；开启单项时只替换该类原料并在失败时回旧，问天保持旧路径。

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

config/datahub.config.json

@@ -0,0 +1,18 @@
+{
+  "schema_version": 1,
+  "base_url": "http://127.0.0.1:8766",
+  "timeout_seconds": 8,
+  "retries": 1,
+  "page_limit": 5000,
+  "stale_seconds_max": 86400,
+  "datasets": {
+    "calendar": { "read": false, "shadow": false },
+    "stocks": { "read": false, "shadow": false },
+    "daily": { "read": false, "shadow": false },
+    "index_daily": { "read": false, "shadow": false },
+    "valuation": { "read": false, "shadow": false },
+    "moneyflow": { "read": false, "shadow": false },
+    "auction": { "read": false, "shadow": false },
+    "status": { "read": false, "shadow": false }
+  }
+}