feat: 重写为 Tauri + React + TypeScript (v4.0)

完全移除旧 C+IUP 代码，改用 Tauri 2.x + React 19 + TypeScript + Rust 技术栈重写。
功能与 v3.1 完全等价：

- React 前端：Tailwind CSS 4、Zustand 状态管理、i18next 国际化
- Rust 后端：winreg 注册表读写、Win32 API FFI 调用
- 核心逻辑：StringList、UndoRedoManager、PathManager、Import/Export
- 深色模式、中英文切换、键盘快捷键、合并预览
- 66 个 Vitest 单元测试

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

src/components/dialogs/ImportDialog.tsx

@@ -0,0 +1,78 @@
+import { useTranslation } from 'react-i18next';
+
+interface ImportDialogProps {
+  open: boolean;
+  hasSystem: boolean;
+  hasUser: boolean;
+  onSelect: (target: 'system' | 'user' | 'both') => void;
+  onCancel: () => void;
+}
+
+export function ImportDialog({
+  open,
+  hasSystem,
+  hasUser,
+  onSelect,
+  onCancel,
+}: ImportDialogProps) {
+  const { t } = useTranslation();
+
+  if (!open) return null;
+
+  return (
+    <div
+      className="fixed inset-0 z-50 flex items-center justify-center"
+      style={{ backgroundColor: 'rgba(0,0,0,0.4)' }}
+      onClick={onCancel}
+    >
+      <div
+        className="rounded-lg p-6"
+        style={{ backgroundColor: 'var(--app-bg)', color: 'var(--app-fg)' }}
+        onClick={(e) => e.stopPropagation()}
+      >
+        <h2 className="text-lg font-semibold mb-4">{t('dialog.importTarget')}</h2>
+        <p className="text-sm mb-4 opacity-70">
+          {hasSystem && `系统变量: ${hasSystem}`}
+          {hasSystem && hasUser && ' | '}
+          {hasUser && `用户变量: ${hasUser}`}
+        </p>
+        <div className="flex flex-col gap-2">
+          {hasSystem && (
+            <button
+              className="px-4 py-2 text-sm rounded border text-left"
+              style={{ borderColor: 'var(--app-border)' }}
+              onClick={() => onSelect('system')}
+            >
+              {t('dialog.importSystem')}
+            </button>
+          )}
+          {hasUser && (
+            <button
+              className="px-4 py-2 text-sm rounded border text-left"
+              style={{ borderColor: 'var(--app-border)' }}
+              onClick={() => onSelect('user')}
+            >
+              {t('dialog.importUser')}
+            </button>
+          )}
+          {hasSystem && hasUser && (
+            <button
+              className="px-4 py-2 text-sm rounded border text-left"
+              style={{ borderColor: 'var(--app-border)' }}
+              onClick={() => onSelect('both')}
+            >
+              {t('dialog.importBoth')}
+            </button>
+          )}
+          <button
+            className="px-4 py-2 text-sm rounded border mt-2"
+            style={{ borderColor: 'var(--app-border)' }}
+            onClick={onCancel}
+          >
+            {t('dialog.cancel')}
+          </button>
+        </div>
+      </div>
+    </div>
+  );
+}