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>

backend/data/datahub/redact.py

@@ -0,0 +1,39 @@
+from __future__ import annotations
+
+from typing import Any
+
+
+SECRET_HINTS = (
+    "token",
+    "password",
+    "secret",
+    "key",
+    "authorization",
+    "credential",
+    "cookie",
+)
+
+
+def redact_value(value: Any, key: str = "", secrets: tuple[str, ...] = ()) -> Any:
+    lowered = key.lower()
+    if any(part in lowered for part in SECRET_HINTS):
+        return "***"
+    if isinstance(value, dict):
+        return {
+            str(item_key): redact_value(item_value, str(item_key), secrets)
+            for item_key, item_value in value.items()
+        }
+    if isinstance(value, list):
+        return [redact_value(item, key, secrets) for item in value]
+    text = str(value) if value is not None and not isinstance(value, (int, float, bool)) else value
+    if isinstance(text, str):
+        return redact_text(text, secrets)
+    return value
+
+
+def redact_text(text: str, secrets: tuple[str, ...] = ()) -> str:
+    redacted = text
+    for secret in secrets:
+        if secret:
+            redacted = redacted.replace(secret, "***")
+    return redacted