refactor: 清理 LOW 问题 — 样式去重、死代码删除、命名修正

- 抽取 buttons.ts 共享按钮样式，消除 3 个组件的重复定义
- store 删除未调用的 canUndo/canRedo 方法
- importFromContent 变量 ext→lower 修正确性
- CSV 导出修复 BOM 重复（exportToCsv 自带 BOM）
- Rust error.rs 添加 allow(dead_code) 消除编译警告

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

src-tauri/src/error.rs

@@ -1,6 +1,7 @@
 use serde::Serialize;
 
-/// 传给前端的统一错误类型（保留供未来使用，当前命令返回 Result<T, String>）
+/// 传给前端的统一错误类型（保留供未来迁移使用，届时所有命令改为返回 Result<T, AppError>）
+#[allow(dead_code)]
 #[derive(Debug, Serialize)]
 pub struct AppError {
     pub message: String,

src/components/toolbar/ActionButtons.tsx

@@ -1,5 +1,6 @@
 import { useTranslation } from 'react-i18next';
 import { useAppStore } from '@/store/app-store';
+import { btnClass, btnStyle } from '@/components/ui/buttons';
 
 interface ActionButtonsProps {
   onNew: () => void;
@@ -24,14 +25,6 @@ export function ActionButtons({
   const isAdmin = useAppStore((s) => s.isAdmin);
   const disabled = !isAdmin;
 
-  const btnClass =
-    'px-3 py-1 text-sm rounded border transition-colors disabled:opacity-40 disabled:cursor-not-allowed';
-  const btnStyle = {
-    backgroundColor: 'var(--app-bg)',
-    color: 'var(--app-fg)',
-    borderColor: 'var(--app-border)',
-  };
-
   return (
     <div className="flex gap-1 flex-wrap">
       <button className={btnClass} style={btnStyle} disabled={disabled} onClick={onNew}>

src/components/toolbar/ToolBar.tsx

@@ -1,5 +1,6 @@
 import { useTranslation } from 'react-i18next';
 import { useAppStore } from '@/store/app-store';
+import { btnClass, btnStyle } from '@/components/ui/buttons';
 import { SearchInput } from './SearchInput';
 import { ActionButtons } from './ActionButtons';
 import { UndoRedoButtons } from './UndoRedoButtons';
@@ -26,14 +27,6 @@ export function ToolBar(props: ToolBarProps) {
   const isAdmin = useAppStore((s) => s.isAdmin);
   const isModified = useAppStore((s) => s.isModified);
 
-  const sysBtnClass =
-    'px-3 py-1 text-sm rounded border transition-colors disabled:opacity-40 disabled:cursor-not-allowed';
-  const sysBtnStyle = {
-    backgroundColor: 'var(--app-bg)',
-    color: 'var(--app-fg)',
-    borderColor: 'var(--app-border)',
-  };
-
   return (
     <div className="space-y-2 pb-2 border-b" style={{ borderColor: 'var(--app-border)' }}>
       {/* 第一行: 搜索 + 系统按钮 */}
@@ -42,38 +35,38 @@ export function ToolBar(props: ToolBarProps) {
         <div className="flex-1" />
         <UndoRedoButtons />
         <button
-          className={sysBtnClass}
+          className={btnClass}
-          style={sysBtnStyle}
+          style={btnStyle}
           disabled={!isAdmin}
           onClick={props.onImport}
         >
           {t('button.import')}
         </button>
-        <button className={sysBtnClass} style={sysBtnStyle} onClick={props.onExport}>
+        <button className={btnClass} style={btnStyle} onClick={props.onExport}>
           {t('button.export')}
         </button>
         <button
-          className={sysBtnClass}
+          className={btnClass}
           style={{
-            ...sysBtnStyle,
+            ...btnStyle,
-            backgroundColor: isModified ? '#2563eb' : sysBtnStyle.backgroundColor,
+            backgroundColor: isModified ? '#2563eb' : btnStyle.backgroundColor,
-            color: isModified ? '#fff' : sysBtnStyle.color,
+            color: isModified ? '#fff' : btnStyle.color,
           }}
           disabled={!isAdmin}
           onClick={props.onSave}
         >
           {t('button.save')}
         </button>
-        <button className={sysBtnClass} style={sysBtnStyle} onClick={props.onCancel}>
+        <button className={btnClass} style={btnStyle} onClick={props.onCancel}>
           {t('button.cancel')}
         </button>
-        <button className={sysBtnClass} style={sysBtnStyle} onClick={props.onHelp}>
+        <button className={btnClass} style={btnStyle} onClick={props.onHelp}>
           {t('button.help')}
         </button>
-        <button className={sysBtnClass} style={sysBtnStyle} onClick={props.onLanguage}>
+        <button className={btnClass} style={btnStyle} onClick={props.onLanguage}>
           {t('button.language')}
         </button>
-        <button className={sysBtnClass} style={sysBtnStyle} onClick={props.onDarkMode}>
+        <button className={btnClass} style={btnStyle} onClick={props.onDarkMode}>
           {t('button.darkMode')}
         </button>
       </div>

src/components/toolbar/UndoRedoButtons.tsx

@@ -1,5 +1,6 @@
 import { useTranslation } from 'react-i18next';
 import { useAppStore } from '@/store/app-store';
+import { btnClass, btnStyle } from '@/components/ui/buttons';
 
 export function UndoRedoButtons() {
   const { t } = useTranslation();
@@ -8,14 +9,6 @@ export function UndoRedoButtons() {
   const undo = useAppStore((s) => s.undo);
   const redo = useAppStore((s) => s.redo);
 
-  const btnClass =
-    'px-3 py-1 text-sm rounded border transition-colors disabled:opacity-40 disabled:cursor-not-allowed';
-  const btnStyle = {
-    backgroundColor: 'var(--app-bg)',
-    color: 'var(--app-fg)',
-    borderColor: 'var(--app-border)',
-  };
-
   return (
     <div className="flex gap-1">
       <button

src/components/ui/buttons.ts

@@ -0,0 +1,7 @@
+export const btnClass = 'px-3 py-1 text-sm rounded border transition-colors disabled:opacity-40 disabled:cursor-not-allowed';
+
+export const btnStyle: React.CSSProperties = {
+  backgroundColor: 'var(--app-bg)',
+  color: 'var(--app-fg)',
+  borderColor: 'var(--app-border)',
+};

src/core/import-export.ts

@@ -193,10 +193,10 @@ export function importFromContent(
   content: string,
   filepath: string,
 ): ImportResult {
-  const ext = filepath.toLowerCase();
+  const lower = filepath.toLowerCase();
-  if (ext.endsWith('.csv')) {
+  if (lower.endsWith('.csv')) {
     return importFromCsv(content);
-  } else if (ext.endsWith('.json')) {
+  } else if (lower.endsWith('.json')) {
     return importFromJson(content);
   } else {
     // TXT 文件：所有路径放入 system（用户后续可选择目标）

src/hooks/use-app-actions.ts

@@ -108,7 +108,7 @@ export function useAppActions(activeTab: TabId, dialogs: DialogState) {
     const content = isCsv ? exportToCsv(data) : exportToJson(data);
     const mime = isCsv ? 'text/csv' : 'application/json';
     const ext = isCsv ? '.csv' : '.json';
-    const blob = new Blob([isCsv ? '' : '', content], { type: mime });
+    const blob = new Blob([content], { type: mime });
     const url = URL.createObjectURL(blob);
     const a = document.createElement('a');
     a.href = url;

src/store/app-store.ts

@@ -39,8 +39,6 @@ interface AppState {
 
   undo: () => void;
   redo: () => void;
-  canUndo: () => boolean;
-  canRedo: () => boolean;
 
   loadPaths: () => Promise<void>;
   savePaths: () => Promise<void>;
@@ -227,9 +225,6 @@ export const useAppStore = create<AppState>((set, get) => ({
     set({ isModified: !(arraysEqual(sysPaths, _savedSys) && arraysEqual(userPaths, _savedUser)) });
   },
 
-  canUndo: () => get().undoRedo.canUndo(),
-  canRedo: () => get().undoRedo.canRedo(),
-
   loadPaths: async () => {
     try {
       set({ isLoading: true });