DeepSeek Harness Plugin: Delayed Message Delivery for Background Sub-Agents

This plugin is designed to address the issue in DeepSeek Harness (DSH) where background sub-agent completion notifications directly interrupt the user when the parent session is busy. Through a “hold-and-release” mechanism, it intercepts settlement, reporting, or message notifications from background agents and delivers them only after the parent session is fully idle, preventing messages from being mixed into the current turn. It takes effect after installation with no configuration required and supports intercepting multiple message types. Users can customize the behavior via `heldKinds` and `maxHoldMs` to avoid accidentally intercepting other notifications or holding messages for extended periods.