DSH Dual Balance: Sidebar Dual Balance Monitoring

The `dsh-dual-balance` plugin aims to address balance fragmentation and inconvenient monitoring for DSH users who use both their official and WorkBuddy accounts. It displays the official DeepSeek balance and WorkBuddy points side by side at the bottom of the sidebar, automatically refreshing every 60 seconds. The plugin supports switching between Chinese and English, shows detailed information on hover, and gracefully handles the case where WorkBuddy is not logged in. Its monetary display strictly follows official rules (truncated to two decimal places), sends no telemetry data, and is privacy-friendly. It can be installed with `dsh plugin add dsh-dual-balance` and requires DSH core 0.2.0-rc.2 or later.