[Feature] 希望增加Bark加密推送的支持

### Description / 功能描述

希望 Certimate 可以支持 Bark 的加密推送
参考：
https://bark.day.app/#/encryption

### Motivation / 请求动机

提高通知隐私性

### Miscellaneous / 其他

_No response_

### Contribution / 贡献代码

- [ ] I am interested in contributing a PR for this! / 我乐意为此提交代码并发起 PR！

Start with the Bark encryption documentation linked in the issue and locate Certimate’s existing Bark notification entry point. The issue names no files or tests, so first identify the integration and its current coverage. Done means Bark notifications can use encryption while existing notification behavior remains supported.

Written by the indexing model from the issue text.