dsh-web-ding: Implementing an Agent Turn-End Notification Sound in the Browser

`dsh-web-ding` is a DSH Web client plugin that synthesizes notification sounds using the Web Audio API to provide idle-state prompts when an Agent turn ends. The host side listens for idle transitions in `agent/status` and emits signals, while the browser side mirrors this namespace. It supports three modes: frontend-only question triggers, Agent turn-end triggers, and Windows 11-style Toast notifications. Messages are stored locally, and volume, frequency, and decay duration are configurable. When using the plugin, be aware of the browser’s autoplay policy and background-tab suspension mechanisms; the AudioContext must be warmed up on first use.