fix(T+托管): 限制健康检查重定向范围

supervisor 的健康探测只允许访问本机地址，避免本机端点重定向到外部网络。\n增加重定向处理器和回归测试，保留现有依赖健康及错误脱敏行为。\n\n影响范围：T+ supervisor 健康检查与运行控制单元测试。\n\nCo-Authored-By: Claude Code <noreply@anthropic.com>

backend/tests/unit/test_tplus_runtime_control.py

@@ -3,6 +3,7 @@
 from datetime import datetime, timedelta
 from threading import Event
 from unittest.mock import MagicMock
+from urllib.error import HTTPError
 
 import pytest
 from sqlalchemy import select
@@ -58,6 +59,28 @@ def test_健康检查拒绝外部地址():
     assert supervisor.health_error(settings) == "后端健康检查地址必须是本机 HTTP 地址"
 
 
+def test_健康检查处理器拒绝外部重定向():
+    request = MagicMock()
+    response = MagicMock()
+    assert supervisor._LocalOnlyRedirectHandler().redirect_request(
+        request, response, 302, "Found", {}, "http://example.com/api/health"
+    ) is None
+
+
+def test_健康检查重定向到外部地址时拒绝(monkeypatch):
+    from app.core.config import Settings
+
+    settings = Settings(_env_file=None, app_secret_key="x" * 32)
+    monkeypatch.setattr(
+        supervisor,
+        "_open_health",
+        lambda *_args, **_kwargs: (_ for _ in ()).throw(
+            HTTPError("http://127.0.0.1/api/health", 302, "Found", {}, None)
+        ),
+    )
+    assert supervisor.health_error(settings) == "系统健康检查或 T+ 连接配置未就绪"
+
+
 @pytest.mark.parametrize("body", [b'[]', b'null', b'{"data":null}', b'{"data":[]}', b'{"data":"bad"}'])
 def test_健康检查结构异常时返回未就绪(monkeypatch, body):
     from app.core.config import Settings
@@ -65,7 +88,7 @@ def test_健康检查结构异常时返回未就绪(monkeypatch, body):
     settings = Settings(_env_file=None, app_secret_key="x" * 32)
     response = MagicMock()
     response.__enter__.return_value.read.return_value = body
-    monkeypatch.setattr(supervisor, "urlopen", lambda *_args, **_kwargs: response)
+    monkeypatch.setattr(supervisor, "_open_health", lambda *_args, **_kwargs: response)
     assert supervisor.health_error(settings) == "系统或依赖尚未就绪"
 
 
@@ -78,7 +101,7 @@ def test_健康检查实际探测来源连接且不泄露错误(monkeypatch, con
                         t_plus_odbc_driver="test-driver")
     response = MagicMock()
     response.__enter__.return_value.read.return_value = b'{"data":{"app":true,"db":true,"redis":true}}'
-    monkeypatch.setattr(supervisor, "urlopen", lambda *_args, **_kwargs: response)
+    monkeypatch.setattr(supervisor, "_open_health", lambda *_args, **_kwargs: response)
     import pyodbc
     monkeypatch.setattr(pyodbc, "drivers", lambda: ["test-driver"])
     engine = MagicMock()