docs(backend): 重构后端README文档，完善项目文档与开发指南

- 全面更新README，添加项目特性、架构设计与技术栈介绍
- 详细补充项目结构说明及模块设计规范
- 增加快速开始步骤，包括环境配置、数据库初始化和服务启动
- 补充主要API模块路径和认证授权使用示例
- 添加开发指南、数据库迁移与测试方法
- 集成监控、日志级别说明及性能监控内容
- 完善Docker、传统部署及Nginx配置示例
- 添加贡献指南和代码规范说明
- 新增MCP模块概述及智能对话API接口文档
- 清理和移除module_ai中旧的mcp_server相关实现代码
- 在api/v1初始化文件中注册AI模块路由
- 修改resource模块，增强资源路径安全检查和文件类型检测逻辑
- 增强资源搜索和上传服务的健壮性及安全性

backend/app/scripts/data/system_menu.json

@@ -2118,5 +2118,68 @@
     "affix": false,
     "redirect": null,
     "description": "初始化数据"
-  } 
+  },
+  {
+    "id": 102,
+    "name": "AI大模型",
+    "type": 1,
+    "icon": "el-icon-DataLine",
+    "order": 8,
+    "permission": null,
+    "route_name": "AI",
+    "route_path": "/ai",
+    "component_path": null,
+    "parent_id": null,
+    "status": true,
+    "keep_alive": false,
+    "hidden": false,
+    "always_show": false,
+    "title": "AI大模型",
+    "params": null,
+    "affix": false,
+    "redirect": "/ai/mcp",
+    "description": "AI大模型管理"
+  },
+  {
+    "id": 103,
+    "name": "MCP智能助手",
+    "type": 2,
+    "icon": "el-icon-DataLine",
+    "order": 1,
+    "permission": "ai:mcp:chat",
+    "route_name": "MCP",
+    "route_path": "/ai/mcp",
+    "component_path": "ai/mcp/index",
+    "parent_id": 102,
+    "status": true,
+    "keep_alive": true,
+    "hidden": false,
+    "always_show": false,
+    "title": "MCP智能助手",
+    "params": null,
+    "affix": false,
+    "redirect": null,
+    "description": "MCP智能助手"
+  },
+  {
+    "id": 104,
+    "name": "智能对话",
+    "type": 3,
+    "icon": null,
+    "order": 1,
+    "permission": "ai:mcp:chat",
+    "route_name": null,
+    "route_path": null,
+    "component_path": null,
+    "parent_id": 103,
+    "status": true,
+    "keep_alive": true,
+    "hidden": false,
+    "always_show": false,
+    "title": "智能对话",
+    "params": null,
+    "affix": false,
+    "redirect": null,
+    "description": "智能对话"
+  }
 ]

backend/app/scripts/data/system_role_menus.json

@@ -403,6 +403,18 @@
     "role_id": 1,
     "menu_id": 101
   },
+  {
+    "role_id": 1,
+    "menu_id": 102
+  },
+  {
+    "role_id": 1,
+    "menu_id": 103
+  },
+  {
+    "role_id": 1,
+    "menu_id": 104
+  },
   {
     "role_id": 2,
     "menu_id": 1