refactor: 代码清理 — 删除 AppError、重命名 replacePaths、修正 detectExportFormat、统一 PATH 长度、优化 BOM 检查、添加同步注释

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

tests/unit/app-store.test.ts

@@ -140,11 +140,11 @@ describe('app-store CRUD', () => {
     expect(useAppStore.getState().sysPaths).toEqual(['C:\\valid']);
   });
 
-  it('importPaths 整体替换列表', () => {
+  it('replacePaths 整体替换列表', () => {
     const store = useAppStore.getState();
     store.addPath('old1', TargetType.USER);
     store.addPath('old2', TargetType.USER);
-    store.importPaths(TargetType.USER, ['new1', 'new2', 'new3']);
+    store.replacePaths(TargetType.USER, ['new1', 'new2', 'new3']);
     expect(useAppStore.getState().userPaths).toEqual(['new1', 'new2', 'new3']);
   });
 

tests/unit/import-export.test.ts

@@ -116,10 +116,11 @@ describe('detectExportFormat', () => {
   it('.csv 检测为 CSV', () => {
     expect(detectExportFormat('data.CSV')).toBe('csv');
   });
-
+  it('.txt 检测为 TXT', () => {
+    expect(detectExportFormat('data.txt')).toBe('txt');
+  });
   it('其他扩展名检测为 JSON', () => {
     expect(detectExportFormat('data.json')).toBe('json');
-    expect(detectExportFormat('data.txt')).toBe('json');
   });
 });