feat: 微服务架构拆分和前后端优化

后端:
- 拆分出 agent_service, runtime_service, trading_service, news_service
- Gateway 模块化拆分 (gateway_*.py)
- 添加 domains/ 领域层
- 新增 control_client, runtime_client
- 更新 start-dev.sh 支持 split 服务模式

前端:
- 完善 API 服务层 (newsApi, tradingApi)
- 更新 vite.config.js
- Explain 组件优化

测试:
- 添加多个服务 app 测试

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/tests/test_agent_service_app.py

@@ -0,0 +1,27 @@
+# -*- coding: utf-8 -*-
+"""Tests for the extracted agent service surface."""
+
+from pathlib import Path
+
+from fastapi.testclient import TestClient
+
+from backend.apps.agent_service import create_app
+
+
+def test_agent_service_routes_include_control_plane_endpoints(tmp_path):
+    app = create_app(project_root=tmp_path)
+
+    paths = {route.path for route in app.routes}
+
+    assert "/health" in paths
+    assert "/api/status" in paths
+    assert "/api/workspaces" in paths
+    assert "/api/guard/pending" in paths
+
+
+def test_agent_service_excludes_runtime_routes(tmp_path):
+    app = create_app(project_root=tmp_path)
+    paths = {route.path for route in app.routes}
+
+    assert "/api/runtime/start" not in paths
+    assert "/api/runtime/gateway/port" not in paths