DeepSeek Harness: Peak-Valley Guard

The DeepSeek Harness (DSH) billing plugin dsh-peak-guard uses host and client plugins to directly short-circuit model request streams during peak hours, preventing additional charges. Core features include peak-hour interception, free operation on weekends and public holidays by default, interception log management, and UI integration. It supports the `/peak` command to toggle the plugin on/off and temporarily allow requests, with optional interception of butler-type calls. Note that this plugin only supports DSH Desktop, and code changes require restarting the application.