新增864 provider并打通server_key配置

- 新增 server_864 独立 provider 目录，接入登录、消息轮询、联系人、群资料、用户资料与朋友圈基础能力

- 扩展 gateway、robot 与配置归一化逻辑，支持 server_864/864 别名和 WECHAT_SERVER_KEY

- 更新配置示例与多版本适配路线图，明确 864 第一版接入范围和后续待补项

wechat_ipad/providers/server_864/friends.py

@@ -0,0 +1,84 @@
+from typing import Union
+
+from wechat_ipad.providers.server_864.base import Server864APIClientBase
+
+
+class FriendMixin(Server864APIClientBase):
+    """864 联系人与通讯录相关接口。"""
+
+    async def get_contact(self, wxid: Union[str, list[str]]) -> Union[dict, list[dict]]:
+        """获取联系人详情，兼容旧调用面。"""
+        detail_list = await self.get_contract_detail(wxid)
+        if isinstance(wxid, str):
+            return detail_list[0] if detail_list else {}
+        return detail_list
+
+    async def get_contract_detail(self, wxid: Union[str, list[str]], chatroom: str = "") -> list:
+        """批量获取联系人详情。"""
+        user_names = [wxid] if isinstance(wxid, str) else list(wxid or [])
+        room_wxid_list = [chatroom] if chatroom else []
+        data = await self._request_data(
+            "post",
+            "/friend/GetContactDetail",
+            json_body={"UserNames": user_names, "RoomWxIDList": room_wxid_list},
+            timeout=30,
+        )
+
+        if isinstance(data, list):
+            return data
+        if not isinstance(data, dict):
+            return []
+
+        contact_list = (
+            data.get("ContactList")
+            or data.get("contactList")
+            or data.get("MemberList")
+            or data.get("memberList")
+            or data.get("UserList")
+            or data.get("userList")
+            or []
+        )
+        return list(contact_list or [])
+
+    async def get_contract_list(self, wx_seq: int = 0, chatroom_seq: int = 0) -> list:
+        """获取通讯录用户名列表。"""
+        data = await self._request_data(
+            "post",
+            "/friend/GetContactList",
+            json_body={
+                "CurrentWxcontactSeq": int(wx_seq),
+                "CurrentChatRoomContactSeq": int(chatroom_seq),
+            },
+            timeout=30,
+        )
+        if isinstance(data, list):
+            return data
+        if not isinstance(data, dict):
+            return []
+        return list(
+            data.get("ContactUsernameList")
+            or data.get("contactUsernameList")
+            or data.get("UserNames")
+            or data.get("userNames")
+            or []
+        )
+
+    async def get_nickname(self, wxid: Union[str, list[str]]) -> Union[str, list[str]]:
+        """根据联系人详情返回昵称。"""
+        data = await self.get_contract_detail(wxid)
+        if isinstance(wxid, str):
+            if not data:
+                return ""
+            nickname = data[0].get("NickName")
+            if isinstance(nickname, dict):
+                return nickname.get("string", "")
+            return nickname or ""
+
+        result = []
+        for contact in data:
+            nickname = contact.get("NickName")
+            if isinstance(nickname, dict):
+                result.append(nickname.get("string", ""))
+            else:
+                result.append(nickname or "")
+        return result