dsh-peak-alert: DeepSeek Peak/Off-Peak Pricing Prompt Plugin

`dsh-peak-alert` is a web front-end plugin for DeepSeek Harness, designed to help users avoid unnecessary costs during peak hours through visual feedback. Based on Beijing time, it automatically identifies peak/off-peak pricing periods and, depending on the configured three intensity levels, displays color cues in the input card background or bottom status bar. It supports weekend and public holiday detection, includes holiday data caching and fault-tolerance mechanisms, and automatically identifies DeepSeek models.