feat: 重构前后端架构，添加Go后端和Python Agent服务

- 新增 Go 语言后端服务(server/)，包含用户认证、Agent管理、数据库连接等API
- 新增 Python Agent 服务(agent/)，实现Agent核心逻辑和工具集
- 前端从原生HTML迁移到Vue.js框架(web/src/)
- 添加 Docker Compose 支持(docker-compose.yml)
- 添加项目架构文档(docs/ARCHITECTURE.md)
- 添加环境变量示例(.env.example)和本地启动脚本(start-local.ps1)

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

agent/app/main.py

@@ -0,0 +1,84 @@
+"""
+X-Agents Python Agent Service
+智能体引擎服务入口
+"""
+import os
+from contextlib import asynccontextmanager
+
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+
+from app.api import routes
+from app.agent.core.agent import AgentManager
+from app.security.audit import AuditLogger
+
+
+# 全局组件
+agent_manager: AgentManager = None
+audit_logger: AuditLogger = None
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    """应用生命周期管理"""
+    global agent_manager, audit_logger
+
+    # 启动时初始化
+    audit_logger = AuditLogger()
+
+    # 初始化 Agent 管理器
+    agent_manager = AgentManager(
+        llm_provider=os.getenv("LLM_PROVIDER", "openai"),
+        openai_api_key=os.getenv("OPENAI_API_KEY"),
+        anthropic_api_key=os.getenv("ANTHROPIC_API_KEY"),
+    )
+
+    # 加载 Agent 配置
+    await agent_manager.load_agents()
+
+    print("Agent service started successfully")
+
+    yield
+
+    # 关闭时清理
+    print("Agent service shutting down")
+
+
+# 创建 FastAPI 应用
+app = FastAPI(
+    title="X-Agents Agent Service",
+    description="AI Agent Engine for X-Agents Platform",
+    version="1.0.0",
+    lifespan=lifespan,
+)
+
+# CORS 中间件
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+# 注册路由
+app.include_router(routes.router, prefix="/agent", tags=["Agent"])
+
+
+@app.get("/health")
+async def health_check():
+    """健康检查"""
+    return {
+        "status": "healthy",
+        "service": "agent",
+        "version": "1.0.0"
+    }
+
+
+@app.get("/")
+async def root():
+    """根路径"""
+    return {
+        "message": "X-Agents Agent Service",
+        "docs": "/docs"
+    }