fix: 脱敏处理 — 移除公司域名和内部实例名

- placeholder: pro-cex-rds → prod-mysql, pro-rds-ro.51aipay.com → mysql.example.com
- test fixtures 同步替换
- 修复 PageHeader 权限检查: 同时检查 routePermissionMap 和 actionPermissionMap
- 前端构建零错误, 后端202测试通过

backend/tests/test_instance_fields.py

@@ -7,9 +7,9 @@ from tests.conftest import auth_header
 async def test_create_instance_with_full_fields(client, admin_token):
     """创建数据源：完整字段"""
     res = await client.post("/api/v1/instances", json={
-        "name": "pro-cex-rds-只读库",
+        "name": "prod-mysql-只读库",
         "db_type": "mysql",
-        "host": "pro-rds-ro.51aipay.com",
+        "host": "mysql.example.com",
         "port": 3306,
         "username": "admin",
         "password": "secret123",