fix(useTheme): Safari ≤13 compatibility — fall back to addListener/removeListener

[Copilot]

Safari 13.1.2 and earlier don't implement MediaQueryList.addEventListener, causing a TypeError: e.addEventListener is not a function crash in useTheme.

变更内容

• useTheme/index.ts: In useCurrentTheme, guard addEventListener/removeEventListener calls with existence checks and fall back to the deprecated addListener/removeListener API supported by older Safari:

if (matchMedia?.addEventListener) {
  matchMedia.addEventListener('change', onThemeChange);
} else if (matchMedia?.addListener) {
  matchMedia.addListener(onThemeChange);
}
// cleanup mirrors the same pattern with removeEventListener → removeListener

• useTheme/__tests__/index.spec.ts: Added test that mocks matchMedia without addEventListener/removeEventListener and asserts addListener/removeListener are invoked instead.

[English Template / 英文模板]

🤔 这个变动的性质是？

• 新特性提交
• 日常 bug 修复
• 站点、文档改进
• 演示代码改进
• TypeScript 定义更新
• 包体积优化
• 性能优化
• 功能增强
• 国际化改进
• 重构
• 代码风格优化
• 测试用例
• 分支合并
• 其他改动（是关于什么的改动？）

🔗 相关 Issue

Safari 13.1.2 下 useTheme 报错：TypeError: e.addEventListener is not a function（MediaQueryList 不支持 addEventListener）。

💡 需求背景和解决方案

问题：Safari ≤13 的 MediaQueryList 未实现标准的 addEventListener/removeEventListener，只支持已废弃的 addListener/removeListener，直接调用导致运行时崩溃。

方案：在订阅/取消订阅系统主题变化时，优先使用标准 API，检测不存在时降级为旧版 API，无需引入任何额外依赖。

📝 更新日志

语言	更新描述
🇺🇸 英文	useTheme: Fixed crash on Safari ≤13 by falling back to deprecated addListener/removeListener when addEventListener is unavailable on MediaQueryList.
🇨🇳 中文	useTheme：修复在 Safari ≤13 中因 MediaQueryList 不支持 addEventListener 导致的运行时报错，降级使用 addListener/removeListener。

☑️ 请求合并前的自查清单

⚠️ 请自检并全部勾选全部选项。⚠️

• 文档已补充或无须补充
• 代码演示已提供或无须提供
• TypeScript 定义已补充或无须补充
• Changelog 已提供或无须提供

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