dsh-update-check: Provides update checks and version visibility for DeepSeek Harness

`dsh-update-check` is an update check plugin for DeepSeek Harness (DSH) used to centrally display the version status of DSH itself and installed plugins in the Profile. This plugin is only responsible for version querying and reporting; it does not perform automatic upgrades, and upgrade decisions are made by the user. Its core functions include: 1. **Version Check**: Queries the current and latest versions of `@deepseek-ai/dsh` and plugins against the npm registry, featuring a failure isolation mechanism to ensure that partial query failures do not affect the overall results. 2. **Multi-platform Access**: Provides the model tool `dsh_check_updates` for Agent proactive queries; adds a new "Update Check" page in the Settings page, displaying a version table and supporting...