feat: 完善通讯录子图，添加API调用工具和精美展示

- 完善通讯录子图nodes.py：优化format_result的展示效果
- 创建通讯录子图API调用工具：api_client.py
- 更新通讯录子图__init__.py，导出所有模块和API客户端
- 所有功能已通过测试验证

backend/app/agent_subgraphs/contact/api_client.py

@@ -0,0 +1,197 @@
+"""
+通讯录子图API调用工具
+Contact Subgraph API Client
+"""
+
+from typing import Dict, Any, Optional, List
+from datetime import datetime
+from dataclasses import dataclass
+
+from .state import Contact, Email
+
+
+# 模拟数据库
+MOCK_CONTACTS_DB = {}
+MOCK_EMAILS_DB = []
+
+
+@dataclass
+class ContactAPIClient:
+    """
+    通讯录API客户端 - 可扩展支持多种后端
+    """
+    
+    def list_contacts_mock(self, user_id: str = "default") -> List[Contact]:
+        """
+        模拟查询联系人列表
+        """
+        if user_id not in MOCK_CONTACTS_DB:
+            # 初始化一些示例数据
+            MOCK_CONTACTS_DB[user_id] = [
+                Contact(
+                    id="1",
+                    name="张三",
+                    phone="13800138000",
+                    email="zhangsan@example.com",
+                    company="科技公司",
+                    position="工程师",
+                    created_at=datetime.now().isoformat()
+                ),
+                Contact(
+                    id="2",
+                    name="李四",
+                    phone="13900139000",
+                    email="lisi@example.com",
+                    company="贸易公司",
+                    position="经理",
+                    created_at=datetime.now().isoformat()
+                ),
+                Contact(
+                    id="3",
+                    name="王五",
+                    phone="13700137000",
+                    email="wangwu@example.com",
+                    company="咨询公司",
+                    position="顾问",
+                    created_at=datetime.now().isoformat()
+                )
+            ]
+        
+        return MOCK_CONTACTS_DB[user_id]
+    
+    def extract_contact_info_mock(self, query: str) -> Optional[Dict[str, Any]]:
+        """
+        模拟从查询中提取联系人信息
+        """
+        # 简化的提取逻辑
+        import re
+        
+        # 提取邮箱
+        email_match = re.search(r'[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}', query)
+        # 提取手机号
+        phone_match = re.search(r'1[3-9]\d{9}', query)
+        # 提取姓名（简单匹配）
+        # 先看是否有"添加"等关键词
+        if any(keyword in query for keyword in ["添加", "add"]):
+            # 尝试提取姓名
+            name = "未知"
+            # 简单的逻辑：去掉关键词、去掉邮箱和电话后剩下的
+            clean_query = query
+            if email_match:
+                clean_query = clean_query.replace(email_match.group(), "")
+            if phone_match:
+                clean_query = clean_query.replace(phone_match.group(), "")
+            clean_query = clean_query.replace("添加", "").replace("add", "").replace("联系人", "").strip()
+            if clean_query:
+                name = clean_query
+            
+            return {
+                "name": name,
+                "phone": phone_match.group() if phone_match else "",
+                "email": email_match.group() if email_match else "",
+                "created_at": datetime.now().isoformat()
+            }
+        
+        return None
+    
+    def save_contact_mock(self, user_id: str, contact: Contact) -> bool:
+        """
+        模拟保存联系人
+        """
+        if user_id not in MOCK_CONTACTS_DB:
+            MOCK_CONTACTS_DB[user_id] = []
+        
+        if not contact.id:
+            contact.id = str(len(MOCK_CONTACTS_DB[user_id]) + 1)
+        
+        MOCK_CONTACTS_DB[user_id].append(contact)
+        return True
+    
+    def list_emails_mock(self) -> List[Email]:
+        """
+        模拟查询邮件列表
+        """
+        global MOCK_EMAILS_DB
+        
+        if not MOCK_EMAILS_DB:
+            # 初始化一些示例邮件
+            MOCK_EMAILS_DB = [
+                Email(
+                    id="1",
+                    subject="会议邀请：AI技术分享",
+                    sender="admin@example.com",
+                    recipients=["user@example.com"],
+                    date=datetime.now().isoformat(),
+                    body="你好，下周一将举办AI技术分享会，欢迎参加。"
+                ),
+                Email(
+                    id="2",
+                    subject="项目进度更新",
+                    sender="manager@example.com",
+                    recipients=["user@example.com"],
+                    date=datetime.now().isoformat(),
+                    body="项目进度良好，继续保持。"
+                )
+            ]
+        
+        return MOCK_EMAILS_DB
+    
+    def generate_email_draft_mock(self, query: str) -> Dict[str, str]:
+        """
+        模拟生成邮件草稿
+        """
+        # 简单的模板生成
+        return {
+            "subject": f"Re: {query}",
+            "recipient": "recipient@example.com",
+            "body": "你好，\n\n这是一封自动生成的邮件草稿。\n\n此致，\n你的助手"
+        }
+    
+    def send_email_mock(self, recipient: str, subject: str, body: str) -> Dict[str, Any]:
+        """
+        模拟发送邮件
+        """
+        # 记录到模拟数据库
+        MOCK_EMAILS_DB.append(
+            Email(
+                id=str(len(MOCK_EMAILS_DB) + 1),
+                subject=subject,
+                sender="me@example.com",
+                recipients=[recipient],
+                date=datetime.now().isoformat(),
+                body=body
+            )
+        )
+        
+        return {
+            "success": True,
+            "message": "邮件发送成功"
+        }
+    
+    def sniff_contacts_mock(self, query: str) -> Dict[str, Any]:
+        """
+        模拟智能嗅探联系人
+        """
+        # 简化的检测逻辑
+        import re
+        
+        emails = re.findall(r'[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}', query)
+        phones = re.findall(r'1[3-9]\d{9}', query)
+        
+        contacts = []
+        for i, email in enumerate(emails):
+            contacts.append({
+                "name": f"联系人{i+1}",
+                "email": email,
+                "phone": phones[i] if i < len(phones) else ""
+            })
+        
+        return {
+            "contacts": contacts,
+            "count": len(contacts),
+            "suggestion": "是否添加这些联系人？"
+        }
+
+
+# 单例实例
+contact_api = ContactAPIClient()