LSP support

### Feature summary

Consider adding support for LSPs

### What problem are you trying to solve?

Honestly surprised this wasn't mentioned yet, but it would be _really_ great to get LSP support for this app. The CLI has it already: https://docs.github.com/en/copilot/concepts/agents/copilot-cli/lsp-servers

### Proposed solution

_No response_

### Workflow impact

_No response_

### Installation context

_No response_

### Additional context

_No response_

首先查看应用的架构和链接的 Copilot CLI LSP 文档，以确定语言服务器支持应放置在哪里。该 issue 未提供文件、入口点、工作流或验收标准，因此请在实现之前定义集成范围和可验证的完成条件。

由索引模型根据 Issue 内容生成。