feat: 接入 Agent 历史记录

- src/services/devopsApi.ts: 增加真实 Agent 调用历史列表接口
- src/components/GlobalAgentDrawer.vue: 抽屉打开时加载持久化历史，并展示用途、状态、问题和上下文摘要

src/services/devopsApi.ts

@@ -503,6 +503,12 @@ export const devopsApi = {
     return data
   },
 
+  async listAgentInvocations(): Promise<AgentInvocation[]> {
+    const { data } = await http.get<AgentInvocation[]>('/agent/invocations')
+    lastDataSource = 'backend'
+    return data
+  },
+
   async getSettings(): Promise<SystemSetting[]> {
     const [health, integrationConfig] = await Promise.all([
       fetchHealth(),