xby-pedestrian: DeepSeek Harness Pedestrian Detection Plugin

The core philosophy of DeepSeek Harness (DSH) is "everything is a plugin." `xby-pedestrian` is a visual plugin for DSH that performs pedestrian detection on input images within a chat context, returning bounding boxes, confidence scores, and labels. The plugin provides three detection interfaces, supporting input via image link, Base64-encoded data, or file path. Before use, obtain an API key from the official website and configure it using the `set_xby_apikey` command. It depends on the Xiaobenyang API service; select the appropriate interface function based on the input data type when using it.