refactor(agent): 将 Summary Model 改造为内置 Sub Agent

- 扩展 AgentMode 类型添加 'internal' 模式
- 新增 summary agent preset (claude-3-5-haiku)
- AgentRegistry 添加 getInternal/listInternalAgents 方法
- CompressionManager 添加 setSummaryModelFromAgentConfig
- Agent 构造函数改用 Registry 配置初始化 Summary 模型
- 清理旧的 SummaryConfig 配置系统
- UI AgentsPanel 分离显示 System/Preset/Custom agents
- UI AgentEditor 为 internal agent 显示简化编辑界面

packages/core/tests/unit/agent/presets/index.test.ts

@@ -14,7 +14,7 @@ import {
 describe('Agent Presets - 预设 Agent', () => {
   describe('presetAgents 集合', () => {
     it('包含所有预设 Agent', () => {
-      expect(Object.keys(presetAgents)).toHaveLength(6);
+      expect(Object.keys(presetAgents)).toHaveLength(7); // includes summary agent
     });
 
     it('包含 general Agent', () => {
@@ -67,7 +67,7 @@ describe('Agent Presets - 预设 Agent', () => {
 
     it('返回正确数量', () => {
       const names = getPresetAgentNames();
-      expect(names).toHaveLength(6);
+      expect(names).toHaveLength(7); // general, explore, code-review, frontend, backend, vision, summary
     });
   });
 
@@ -192,9 +192,9 @@ describe('Agent Presets - 预设 Agent', () => {
       });
     });
 
-    it('mode 值是 subagent 或 primary', () => {
+    it('mode 值是有效的 AgentMode', () => {
       Object.entries(presetAgents).forEach(([name, agent]) => {
-        expect(['subagent', 'primary'], `${name} mode 无效`).toContain(agent.mode);
+        expect(['subagent', 'primary', 'all', 'internal'], `${name} mode 无效`).toContain(agent.mode);
       });
     });
   });

packages/core/tests/unit/core/agent.test.ts

@@ -38,6 +38,7 @@ vi.mock('ai', () => ({
 vi.mock('../../../src/agent/index.js', () => ({
   agentRegistry: {
     get: vi.fn(),
+    getInternal: vi.fn(() => null), // Returns null by default - no summary agent configured
   },
   AgentExecutor: vi.fn().mockImplementation(() => ({
     execute: vi.fn().mockResolvedValue({