dsh-provider-quota: DSH Web GUI Model Provider Quota Query Plugin

`dsh-provider-quota` is a plugin for the DSH Web GUI designed to query model provider quotas and resolve the issue of scattered balances. It centrally displays account balances, package information, and token usage for providers such as DeepSeek, OpenAI, Moonshot, Zhipu, OpenRouter, SiliconFlow, and Z.AI via a sidebar real-time panel (auto-polling every 60 seconds) and the "Settings → Model Quota" page. The plugin supports both Chinese and English interfaces, and API keys are parsed only on the host side to ensure browser-side security. Installation requires adding the plugin to the `web` profile and configuring the bundle layer stack, followed by restarting the service. Users only need to configure keys on the model page to check status manually or automatically via the sidebar or settings page.