feat: 按机器人选择 Agent Preset

在九个渠道的设置页卡片上选择 Host 已有预设；未选则跟随默认，只影响之后新建的会话。

Co-authored-by: Cursor <cursoragent@cursor.com>

plugin-src/host/channels/shared/workspace-rpc.mjs

@@ -20,6 +20,7 @@ export function publicWorkspaceError(error) {
     'workspace-not-found',
     'workspace-not-directory',
     'workspace-bot-not-found',
+    'agent-preset-invalid',
   ].includes(error?.code)) return null;
   return { code: error.code, message: error.message };
 }