feat: 新增 6 个工具并重组目录结构

新增工具:
- grep_content: 在文件内容中搜索文本/正则表达式
- get_file_info: 获取文件元信息（大小、权限、时间等）
- move_file: 移动或重命名文件/目录
- copy_file: 复制文件或目录（支持递归）
- delete_file: 删除文件或目录
- create_directory: 创建目录

目录重组:
- src/tools/shell/ - Shell 相关工具（bash）
- src/tools/filesystem/ - 文件系统工具（12个）
- 每个子目录有独立的 index.ts 导出

权限系统扩展:
- 新增操作类型: grep, info, move, copy, mkdir
- 读取类操作默认允许，写入类操作需要确认

src/tools/filesystem/delete_file.ts

@@ -0,0 +1,91 @@
+import * as fs from 'fs/promises';
+import * as path from 'path';
+import type { Tool, ToolResult } from '../../types/index.js';
+import { loadDescription } from '../load_description.js';
+import { getPermissionManager } from '../../permission/index.js';
+
+export const deleteFileTool: Tool = {
+  name: 'delete_file',
+  description: loadDescription('delete_file'),
+  parameters: {
+    path: {
+      type: 'string',
+      description: '要删除的文件或目录的路径',
+      required: true,
+    },
+    recursive: {
+      type: 'boolean',
+      description: '是否递归删除目录（默认 false）',
+      required: false,
+    },
+  },
+  execute: async (params: Record<string, unknown>): Promise<ToolResult> => {
+    const filePath = params.path as string;
+    const recursive = (params.recursive as boolean) || false;
+    const cwd = process.cwd();
+
+    const absolutePath = path.isAbsolute(filePath)
+      ? filePath
+      : path.join(cwd, filePath);
+
+    // 权限检查
+    const permissionManager = getPermissionManager();
+    const permResult = await permissionManager.checkFilePermission({
+      operation: 'delete',
+      path: absolutePath,
+      workdir: cwd,
+    });
+
+    if (!permResult.allowed) {
+      if (permResult.needsConfirmation) {
+        return {
+          success: false,
+          output: '',
+          error: `需要用户确认: 删除 ${absolutePath}\n原因: ${permResult.reason || '需要权限确认'}`,
+        };
+      }
+      return {
+        success: false,
+        output: '',
+        error: `权限被拒绝: ${permResult.reason || '不允许删除此文件'}`,
+      };
+    }
+
+    try {
+      const stats = await fs.stat(absolutePath);
+
+      if (stats.isDirectory()) {
+        if (!recursive) {
+          // 检查目录是否为空
+          const entries = await fs.readdir(absolutePath);
+          if (entries.length > 0) {
+            return {
+              success: false,
+              output: '',
+              error: `目录不为空。如需删除非空目录，请设置 recursive: true`,
+            };
+          }
+          await fs.rmdir(absolutePath);
+        } else {
+          await fs.rm(absolutePath, { recursive: true });
+        }
+        return {
+          success: true,
+          output: `已删除目录: ${absolutePath}`,
+        };
+      } else {
+        await fs.unlink(absolutePath);
+        return {
+          success: true,
+          output: `已删除文件: ${absolutePath}`,
+        };
+      }
+    } catch (error) {
+      return {
+        success: false,
+        output: '',
+        error: error instanceof Error ? error.message : String(error),
+      };
+    }
+  },
+};