refactor: 拆分 ai_cli.py 为模块化 xcli_core 包

将 4130 行的单文件拆分为 13 个职责清晰的模块:
- constants.py: 常量 + 可选依赖导入
- sandbox.py: 安全代码沙箱 (AST检查器 + 子进程隔离)
- config.py: 配置管理 + 日志
- plugin_manager.py: LiuginManager 插件管理器
- cli_base.py: BaseAICLI 基类 (初始化/引擎/插件/命令)
- cli_clawli.py: ClawliMixin 远程模式
- cli_tools.py: ToolMixin 工具调用
- cli_code_exec.py: CodeExecMixin 代码沙箱执行
- cli_display.py: DisplayMixin 显示/输出/图片/帮助
- cli_history.py: HistoryMixin 聊天记录
- cli_core.py: AICLI 主类 + 对话循环 + main()
- tui.py: Textual TUI 界面
- __init__.py: 包导出汇总

ai_cli.py 保留为入口文件 (11行), 根目录整洁。
原逻辑完全不变, 仅做结构拆分。

xcli_core/constants.py

@@ -0,0 +1,94 @@
+# 常量定义
+WEB_SERVER_DEFAULT_PORT = 8080
+MAX_FILE_SIZE = 52428800  # 50MB
+MAX_VIDEO_DURATION = 10000  # 10秒
+VIDEO_FRAME_DELAY = 0.04  # 40毫秒
+LOVE_FILE_PATH = "love.txt"
+DEFAULT_MAX_HISTORY = 999999  # 无限制对话历史
+
+import os
+import sys
+import importlib.util
+import json
+import re
+import requests
+import shutil
+import time
+import threading
+from concurrent.futures import ThreadPoolExecutor, as_completed
+from openai import OpenAI
+from colorama import init, Fore, Style
+
+# tkinter 仅在视频播放功能中使用，服务器环境可能不可用
+try:
+    import tkinter as tk
+    from tkinter import ttk
+    TKINTER_AVAILABLE = True
+except ImportError:
+    TKINTER_AVAILABLE = False
+
+# cv2 仅在视频播放功能中使用
+try:
+    import cv2
+    CV2_AVAILABLE = True
+except ImportError:
+    CV2_AVAILABLE = False
+
+import numpy as np
+from http.server import HTTPServer, BaseHTTPRequestHandler
+from urllib.parse import urlparse, parse_qs
+import socket
+import webbrowser
+from datetime import datetime
+import logging
+
+# 图像显示相关（可选）
+try:
+    from PIL import Image
+    PIL_AVAILABLE = True
+except ImportError:
+    PIL_AVAILABLE = False
+
+try:
+    from ascii_magic import AsciiArt
+    ASCII_MAGIC_AVAILABLE = True
+except ImportError:
+    ASCII_MAGIC_AVAILABLE = False
+
+# WebSocket 服务端
+try:
+    import websocket_server
+    WEBSOCKET_AVAILABLE = True
+except ImportError:
+    WEBSOCKET_AVAILABLE = False
+
+# Clawli 独立进程服务器
+try:
+    import clawli_server
+    CLAWLI_SERVER_AVAILABLE = True
+except ImportError:
+    CLAWLI_SERVER_AVAILABLE = False
+
+# 统一工具管理器 - 支持 Liugin 和 Skill 双协议
+try:
+    from unified_tool_manager import UnifiedToolManager
+    UNIFIED_TOOL_MANAGER_AVAILABLE = True
+except ImportError:
+    UNIFIED_TOOL_MANAGER_AVAILABLE = False
+
+# Textual TUI 支持
+import asyncio
+from typing import Optional
+from io import StringIO
+
+try:
+    from textual.app import App, ComposeResult
+    from textual.containers import Container, Horizontal, Vertical, VerticalScroll
+    from textual.widgets import Header, Footer, Input, RichLog, Static, Button, Tree
+    from textual.widgets.tree import TreeNode
+    from textual.binding import Binding
+    from textual.events import Mount
+    TEXTUAL_AVAILABLE = True
+except ImportError:
+    TEXTUAL_AVAILABLE = False
+    print(f"{Fore.YELLOW}Textual 未安装，TUI 模式不可用。请运行: pip install textual{Style.RESET_ALL}")