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>

tests/unit/path-manager.test.ts

@@ -1,100 +1,31 @@
-import { describe, it, expect, beforeEach } from 'vitest';
-import {
-  pathRemoveAt,
-  pathMoveUp,
-  pathMoveDown,
-  pathClean,
-  batchRemoveAt,
-} from '../../src/core/path-manager';
-import { StringList } from '../../src/core/string-list';
+import { describe, it, expect } from 'vitest';
+import { pathClean } from '../../src/core/path-manager';
 
-// 模拟验证函数：所有路径都"有效"
 const alwaysValid = () => true;
-
-// 模拟验证函数：C:\\Invalid 无效
 const validateFn = (path: string) => !path.includes('Invalid');
 
-describe('pathRemoveAt', () => {
-  it('删除指定索引', () => {
-    const list = StringList.fromArray(['a', 'b', 'c']);
-    pathRemoveAt(list, 1);
-    expect(list.toArray()).toEqual(['a', 'c']);
-  });
-});
-
-describe('pathMoveUp', () => {
-  it('上移元素', () => {
-    const list = StringList.fromArray(['a', 'b', 'c']);
-    pathMoveUp(list, 1);
-    expect(list.toArray()).toEqual(['b', 'a', 'c']);
-  });
-
-  it('第一个元素不能上移', () => {
-    const list = StringList.fromArray(['a', 'b']);
-    expect(pathMoveUp(list, 0)).toBe(false);
-    expect(list.toArray()).toEqual(['a', 'b']);
-  });
-
-  it('无效索引不能上移', () => {
-    const list = StringList.fromArray(['a']);
-    expect(pathMoveUp(list, -1)).toBe(false);
-    expect(pathMoveUp(list, 5)).toBe(false);
-  });
-});
-
-describe('pathMoveDown', () => {
-  it('下移元素', () => {
-    const list = StringList.fromArray(['a', 'b', 'c']);
-    pathMoveDown(list, 0);
-    expect(list.toArray()).toEqual(['b', 'a', 'c']);
-  });
-
-  it('最后一个元素不能下移', () => {
-    const list = StringList.fromArray(['a', 'b']);
-    expect(pathMoveDown(list, 1)).toBe(false);
-  });
-});
-
-describe('batchRemoveAt', () => {
-  it('批量删除（按从大到小排序）', () => {
-    const list = StringList.fromArray(['a', 'b', 'c', 'd', 'e']);
-    batchRemoveAt(list, [0, 2, 4]);
-    expect(list.toArray()).toEqual(['b', 'd']);
-  });
-
-  it('删除乱序索引', () => {
-    const list = StringList.fromArray(['a', 'b', 'c', 'd']);
-    batchRemoveAt(list, [3, 0]);
-    expect(list.toArray()).toEqual(['b', 'c']);
-  });
-});
-
 describe('pathClean', () => {
   it('移除无效路径', () => {
-    const list = StringList.fromArray(['C:\\Valid', 'C:\\Invalid', 'D:\\Valid']);
-    const removed = pathClean(list, validateFn);
-    expect(list.toArray()).toEqual(['C:\\Valid', 'D:\\Valid']);
+    const [kept, removed] = pathClean(['C:\\Valid', 'C:\\Invalid', 'D:\\Valid'], validateFn);
+    expect(kept).toEqual(['C:\\Valid', 'D:\\Valid']);
     expect(removed).toEqual(['C:\\Invalid']);
   });
 
-  it('移除重复路径（保留一个）', () => {
-    const list = StringList.fromArray(['C:\\Valid', 'C:\\Valid', 'D:\\Valid']);
-    const removed = pathClean(list, alwaysValid);
-    expect(list.length).toBe(2);
-    expect(removed.length).toBeGreaterThanOrEqual(1);
+  it('移除重复路径保留第一个', () => {
+    const [kept, removed] = pathClean(['C:\\Valid', 'C:\\Valid', 'D:\\Valid'], alwaysValid);
+    expect(kept.length).toBe(2);
+    expect(removed.length).toBe(1);
   });
 
   it('全部有效无变化', () => {
-    const list = StringList.fromArray(['C:\\a', 'D:\\b']);
-    const removed = pathClean(list, alwaysValid);
-    expect(list.toArray()).toEqual(['C:\\a', 'D:\\b']);
+    const [kept, removed] = pathClean(['C:\\a', 'D:\\b'], alwaysValid);
+    expect(kept).toEqual(['C:\\a', 'D:\\b']);
     expect(removed.length).toBe(0);
   });
 
   it('全部无效全部移除', () => {
-    const list = StringList.fromArray(['C:\\Invalid1', 'C:\\Invalid2']);
-    const removed = pathClean(list, validateFn);
-    expect(list.length).toBe(0);
+    const [kept, removed] = pathClean(['C:\\Invalid1', 'C:\\Invalid2'], validateFn);
+    expect(kept.length).toBe(0);
     expect(removed.length).toBe(2);
   });
 });