dsh-overtime-limit: Overtime Duration Compliance Validation Plugin

`dsh-overtime-limit` is a pure Node.js plugin for DeepSeek Harness, designed to address working-hours compliance checking requirements. With no network dependencies, the plugin registers the `overtime_limit` tool, enabling callers to precisely calculate overtime hours based on parameters and return detailed compliance results with cited legal provisions. It is released under the MIT license and is suitable for use in automated compliance checking scenarios.