feat: Mcp服务器连接状态显示

### 使用场景 / Use case

关于mcp功能：
希望显示当前连接状态。

### 当前问题 / Current limitation

无法快速判断mcp服务器是否连接。

### 期望方案 / Proposed solution

_No response_

### 已考虑的替代方案 / Alternatives considered

_No response_

The issue names no file, test, or entry point. Start by locating the MCP server connection handling and the UI that represents integrations, then trace how connection changes reach the display. Done means users can quickly distinguish the current MCP server connection state.

Written by the indexing model from the issue text.