xby-database-access-service: Database Metadata Retrieval

`xby-database-access-service` is an MIT-licensed plugin for DeepSeek Harness (DSH) designed to address agent interaction with databases. Its core features include setting an API key, listing tables, retrieving table schemas, and executing SQL queries. Users must first register on the official Xiaoben Yang website to obtain a key, then install and configure the plugin via command, enabling step-by-step database operations within chat. Note that the plugin runs with the permissions of the current process; ensure that it is used only in a trusted environment.