Integrate CalDAV Calendar Read and Write Functions for DeepSeek Harness with dsh-calendar

### 正式翻译（符合技术文档规范）： dsh-calendar is a DSH tool plugin maintained by STARDUSTLC666, with the npm version 0.3.2. It provides five functions including list/create/update/delete/search via CalDAV, and is compatible with Google, iCloud, Nextcloud and custom endpoints. The installation command on the catalog page is `dsh plugin add github:stardustlc666/dsh-calendar`. The configuration is written in `cordis.patch.yml`, and the plugin will not crash on startup without a configuration. The license declared in package.json is MIT. The plugin runs with the permissions of the current dsh process, so you should check the source code and license before installation.