feat: 升级至 v0.3.12 — 文件与代码类工具全面优化（16 项）

【阶段一 · 紧急修复 F1】
- F1-1 file_editor regex 计数 bug：强制 g 标志 + 同一 RegExp 实例做 match+replace
- F1-2 code_search 统一 safeResolvePath（含路径遍历 + MEMORY.md 拦截）
- F1-3 git_commit amend 模式：message 可选 + --no-edit 防止编辑器 hang
- F1-4 write_file append 模式原子化：显式 open(O_APPEND)+write+fsync+close

【阶段二 · 增强现有工具 F2】
- F2-1 read_file 智能编码检测：BOM(UTF-8/UTF-16 LE/BE) + GBK 降级
- F2-2 read_file 支持 tail 模式（读取末尾 N 行，适用日志）
- F2-3 search_files 二进制过滤 + 智能编码检测
- F2-4 search_files 多 glob 匹配（逗号分隔，如 *.ts,*.js）
- F2-5 file_editor 新增 find_replace 操作（字面量替换，规避正则歧义）
- F2-6 file_editor regex 支持跨行匹配（multiline 参数）
- F2-7 file_editor 新增 backup 参数（编辑前 .bak 备份）

【阶段三 · 新增工具 F3】
- F3-1 file_move：双路径校验 + overwrite + 自动建父目录 + rename 原子
- F3-2 file_info：大小/时间/类型/编码/二进制/权限位

【阶段四 · 优化 F4】
- F4-1 diff_viewer Uint32Array→Uint16Array（省一半内存）+ safeResolvePath + 智能编码
- F4-2 错误处理统一：diff-viewer/file-editor/code-search catch 块改用 extractErrorMessage

【阶段五 · 验证 F5】
- tsc --noEmit 类型检查通过
- 人工审查通过：路径校验/错误处理/原子性/资源释放/权限策略/导出注册

工具数量：13 → 15（新增 file_move / file_info）

electron/harness/tools/built-in/code-search.ts

@@ -12,12 +12,13 @@
 
 import { execFile } from 'child_process';
 import { promisify } from 'util';
-import { resolve } from 'path';
 import log from 'electron-log';
 import type { IMetonaTool, ToolExecutionContext } from '../../types/metona-tool';
 import type { MetonaToolDef } from '../../../harness/types';
 import { MetonaToolCategory, MetonaRiskLevel } from '../../../harness/types';
-import { isPathWithinWorkspace } from './file-guard';
+// F1-2: 统一用 safeResolvePath（含 isPathWithinWorkspace + MEMORY.md 拦截）
+// F4-2: 引入 extractErrorMessage 统一错误处理
+import { safeResolvePath, extractErrorMessage } from './file-guard';
 
 const execFileAsync = promisify(execFile);
 
@@ -60,31 +61,37 @@ export class CodeSearchTool implements IMetonaTool {
   };
 
   async execute(args: Record<string, unknown>, context: ToolExecutionContext): Promise<unknown> {
-    const pattern = args.pattern as string;
-    if (typeof pattern !== 'string' || !pattern) {
-      return { results: [], count: 0, error: 'Pattern is required and must be a string' };
-    }
-    if (pattern.length > 500) {
-      return { results: [], count: 0, error: 'Pattern too long (max 500 chars)' };
-    }
+    // F4-2: 外层 try-catch 防止 safeResolvePath 抛出异常向上传播
+    // （read_file/write_file/list_directory 均有外层 try-catch，code_search 此前缺失）
+    try {
+      const pattern = args.pattern as string;
+      if (typeof pattern !== 'string' || !pattern) {
+        return { results: [], count: 0, error: 'Pattern is required and must be a string' };
+      }
+      if (pattern.length > 500) {
+        return { results: [], count: 0, error: 'Pattern too long (max 500 chars)' };
+      }
 
-    const searchPath = args.path
-      ? this.resolveSearchPath(args.path as string, context.workspacePath)
-      : context.workspacePath;
-    const fileGlob = args.file_glob as string | undefined;
-    const caseSensitive = (args.case_sensitive as boolean) ?? false;
-    const contextBefore = Math.min(5, Math.max(0, (args.context_before as number) ?? 0));
-    const contextAfter = Math.min(5, Math.max(0, (args.context_after as number) ?? 0));
-    const maxResults = Math.min(200, Math.max(1, (args.max_results as number) ?? 50));
+      const searchPath = args.path
+        ? safeResolvePath(args.path as string, context.workspacePath)
+        : context.workspacePath;
+      const fileGlob = args.file_glob as string | undefined;
+      const caseSensitive = (args.case_sensitive as boolean) ?? false;
+      const contextBefore = Math.min(5, Math.max(0, (args.context_before as number) ?? 0));
+      const contextAfter = Math.min(5, Math.max(0, (args.context_after as number) ?? 0));
+      const maxResults = Math.min(200, Math.max(1, (args.max_results as number) ?? 50));
 
-    const opts = { fileGlob, caseSensitive, contextBefore, contextAfter, maxResults };
+      const opts = { fileGlob, caseSensitive, contextBefore, contextAfter, maxResults };
 
-    // 优先使用 ripgrep，回退到 JS 实现
-    const hasRg = await this.checkRipgrep();
-    if (hasRg) {
-      return this.searchWithRipgrep(pattern, searchPath, opts, context);
+      // 优先使用 ripgrep，回退到 JS 实现
+      const hasRg = await this.checkRipgrep();
+      if (hasRg) {
+        return this.searchWithRipgrep(pattern, searchPath, opts, context);
+      }
+      return this.searchWithJs(pattern, searchPath, opts, context);
+    } catch (error) {
+      return { results: [], count: 0, error: extractErrorMessage(error), success: false };
     }
-    return this.searchWithJs(pattern, searchPath, opts, context);
   }
 
   /** 使用 ripgrep 子进程搜索 */
@@ -217,12 +224,4 @@ export class CodeSearchTool implements IMetonaTool {
       limit: opts.maxResults,
     }, context);
   }
-
-  private resolveSearchPath(filePath: string, workspacePath: string): string {
-    const resolved = resolve(workspacePath, filePath);
-    if (!isPathWithinWorkspace(filePath, workspacePath)) {
-      throw new Error(`Path traversal detected: ${filePath}`);
-    }
-    return resolved;
-  }
 }