dsh-sound: DSH Web UI Event Sound Reminder Plugin

dsh-sound is a Web UI plugin for DeepSeek Harness (DSH) designed to reduce developer reliance on interface status through auditory alerts. The plugin covers six independent event types: task completion, approval requests, user questions, plan review, blocked goals, and background failures, supporting the individual configuration of 0-100% volume levels and sound sources for each. Sound sources include built-in synthesized sounds (such as Ding and Chime), mute, or local MP3/WAV files, with local files stored in IndexedDB to save quota. The plugin provides a settings panel that supports configuring a global toggle, event details, and configuration import/export. In multi-tab scenarios, it utilizes BroadcastChannel to ensure events trigger only once and falls back to snapshot comparison when the event stream is unavailable. Installation requires DSH.