feat: 添加租户工具配置系统

- 新增 platform_tool_configs 表和 ToolConfig Model
- 新增工具配置 CRUD API (/api/tool-configs)
- 租户详情页添加工具配置管理 Tab
- 修复查看 Token 显示问题，添加专用获取接口

backend/app/models/tool_config.py

@@ -0,0 +1,21 @@
+"""租户工具配置模型"""
+from datetime import datetime
+from sqlalchemy import Column, Integer, String, Text, SmallInteger, TIMESTAMP
+from ..database import Base
+
+
+class ToolConfig(Base):
+    """租户工具配置表"""
+    __tablename__ = "platform_tool_configs"
+    
+    id = Column(Integer, primary_key=True, autoincrement=True)
+    tenant_id = Column(String(50), nullable=False, comment="租户ID")
+    tool_code = Column(String(50), nullable=True, comment="工具代码（NULL 表示租户级共享配置）")
+    config_type = Column(String(30), nullable=False, comment="配置类型：datasource / jssdk / webhook / params")
+    config_key = Column(String(100), nullable=False, comment="配置键名")
+    config_value = Column(Text, comment="配置值（明文或加密）")
+    is_encrypted = Column(SmallInteger, default=0, comment="是否加密存储")
+    description = Column(String(255), comment="配置说明")
+    status = Column(SmallInteger, default=1)
+    created_at = Column(TIMESTAMP, default=datetime.now)
+    updated_at = Column(TIMESTAMP, default=datetime.now, onupdate=datetime.now)