feat: 添加用户手册功能

- 新增用户手册 Markdown 文档及配套截图
   - 新增打开用户手册命令
   - 在侧边栏和主面板中集成用户手册入口
   - 优化用户手册打开方式，支持 Markdown 预览

src/views/webviewContent.ts

@@ -18,6 +18,11 @@ import {
   getMessageAreaScript,
 } from "./messageArea";
 import { getAgentCardStyles, getAgentCardScript } from "./agentCard";
+import {
+  getMoreOptionsComponentContent,
+  getMoreOptionsComponentStyles,
+  getMoreOptionsComponentScript,
+} from "./moreOptionsComponent";
 import {
   getProgressBarContent,
   getProgressBarStyles,
@@ -110,6 +115,7 @@ export function getWebviewContent(
     }
     ${getMessageAreaStyles()}
     ${getAgentCardStyles()}
+    ${getMoreOptionsComponentStyles()}
     ${getWaveformPreviewContent()}
     ${getConversationHistoryBarStyles()}
     ${getProgressBarStyles()}
@@ -921,6 +927,7 @@ export function getWebviewContent(
 
     ${getMessageAreaScript()}
     ${getAgentCardScript()}
+    ${getMoreOptionsComponentScript()}
     ${getWaveformPreviewScript()}
     ${getConversationHistoryBarScript()}
     ${getProgressBarScript()}