refactor: 全面代码质量提升 — StringList→string[], strict 模式, 死代码清理

架构重构:
- StringList 类替换为不可变 string[]（消除 dataVersion hack，Zustand 自然检测变化）
- UndoRedoManager.undo/redo 返回新数组而非原地修改
- 删除 dataVersion 字段和 _bumpVersion()
- 启用 TypeScript strict 模式

死代码清理:
- 删除 string-list.ts, string-list.test.ts, use-path-validation.ts
- Rust AppError 保留供未来使用

功能修复:
- importFromJson 添加 try/catch
- handleClean 使用真实格式验证替代 () => true
- savePaths 保存前调用 backup_registry，处理部分保存失败
- importFromJson 校验非 object 类型输入

i18n 完善:
- MergePreview/StatusBar 硬编码中文 → t() 调用
- 新增 merge.* 和 status.* 翻译键

Rust 改进:
- registry.rs 抽取 load_paths/save_paths 通用函数，消除重复
- registry 新增 6 个单元测试（split/join/roundtrip）
- backup.rs 时间戳加毫秒防覆盖，回退路径改为 home_dir

元数据:
- package.json 名称→patheditor, 版本→4.0.0
- 新增 CHANGELOG.md
- 移除 UndoRedoButtons 废弃注释
- tsconfig 添加 strict:true

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/components/path-list/MergePreview.tsx

@@ -1,22 +1,22 @@
 import { useMemo } from 'react';
 import { useAppStore } from '@/store/app-store';
+import { useTranslation } from 'react-i18next';
 
 export function MergePreview() {
-  const dataVersion = useAppStore((s) => s.dataVersion);
-  void dataVersion; // 订阅版本号强制重渲染
   const sysPaths = useAppStore((s) => s.sysPaths);
   const userPaths = useAppStore((s) => s.userPaths);
   const searchQuery = useAppStore((s) => s.searchQuery);
+  const { t } = useTranslation();
 
   const allPaths = useMemo(() => {
-    const result: { path: string; source: '系统' | '用户'; index: number }[] = [];
-    sysPaths.all.forEach((p, i) => result.push({ path: p, source: '系统' as const, index: i }));
-    userPaths.all.forEach((p, i) => result.push({ path: p, source: '用户' as const, index: i }));
+    const result: { path: string; source: string; index: number }[] = [];
+    sysPaths.forEach((p, i) => result.push({ path: p, source: t('merge.system'), index: i }));
+    userPaths.forEach((p, i) => result.push({ path: p, source: t('merge.user'), index: i }));
 
     if (!searchQuery) return result;
     const q = searchQuery.toLowerCase();
     return result.filter((r) => r.path.toLowerCase().includes(q));
-  }, [sysPaths, userPaths, searchQuery]);
+  }, [sysPaths, userPaths, searchQuery, t]);
 
   return (
     <div className="flex-1 overflow-auto">
@@ -27,8 +27,8 @@ export function MergePreview() {
             style={{ backgroundColor: 'var(--app-list-alt)', color: 'var(--app-fg)' }}
           >
             <th className="w-10 px-2 py-1">#</th>
-            <th className="px-2 py-1">路径</th>
-            <th className="w-16 px-2 py-1">来源</th>
+            <th className="px-2 py-1">{t('dialog.pathLabel')}</th>
+            <th className="w-16 px-2 py-1">{t('merge.source')}</th>
           </tr>
         </thead>
         <tbody>