xby-caltrain: A GTFS-Based Caltrain Train Schedule Query Service

`xby-caltrain` is a network tool plugin for DeepSeek Harness (DSH), designed to quickly integrate Caltrain timetables query functionality into an agent. Built on GTFS data, it provides three core tools: `set_xby_apikey`, which sets and persists the API key; `next_trains`, which queries train departures (supporting station abbreviations or full names); and `list_stations`, which lists all available stations. It must be installed using the `dsh plugin` command. When using it, note that the API key must be configured first, and station names must match the system’s supported list (case-insensitive, but potentially sensitive to spaces).