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/group.py

@@ -0,0 +1,90 @@
+from typing import Any, Union
+
+from wechat_ipad.providers.server_864.base import Server864APIClientBase
+
+
+class ChatroomMixin(Server864APIClientBase):
+    """864 群聊相关接口。"""
+
+    async def get_chatroom_info(self, chatroom: str) -> dict:
+        """获取单个群详情。"""
+        data = await self._request_data(
+            "post",
+            "/group/GetChatRoomInfo",
+            json_body={"ChatRoomWxIdList": [chatroom]},
+            timeout=30,
+        )
+        if isinstance(data, list):
+            return dict(data[0] or {}) if data else {}
+        if not isinstance(data, dict):
+            return {}
+
+        contact_list = data.get("ContactList") or data.get("contactList") or []
+        if contact_list:
+            return dict(contact_list[0] or {})
+        return dict(data)
+
+    async def get_chatroom_member_list(self, chatroom: str) -> list[dict]:
+        """获取群成员列表。"""
+        data = await self._request_data(
+            "post",
+            "/group/GetChatroomMemberDetail",
+            json_body={"ChatRoomName": chatroom},
+            timeout=30,
+        )
+        if isinstance(data, list):
+            return list(data)
+        if not isinstance(data, dict):
+            return []
+        return list(
+            data.get("ChatRoomMember")
+            or data.get("chatRoomMember")
+            or (data.get("NewChatroomData") or {}).get("ChatRoomMember", [])
+            or (data.get("newChatroomData") or {}).get("chatRoomMember", [])
+            or data.get("MemberList")
+            or []
+        )
+
+    async def get_chatroom_announce(self, chatroom: str) -> dict:
+        """获取群公告详情。"""
+        data = await self._request_data(
+            "post",
+            "/group/GetChatRoomInfoDetail",
+            json_body={"ChatRoomName": chatroom},
+            timeout=30,
+        )
+        return dict(data or {})
+
+    async def get_chatroom_qrcode(self, chatroom: str) -> dict[str, Any]:
+        """获取群二维码。"""
+        data = await self._request_data(
+            "post",
+            "/group/GetChatroomQrCode",
+            json_body={"ChatRoomName": chatroom},
+            timeout=30,
+        )
+        return {
+            "base64": str(self._pick_first(data, "QrCode", "qrcode", "QrCodeBase64", "base64") or ""),
+            "description": str(self._pick_first(data, "Desc", "desc", "Description", "description") or ""),
+        }
+
+    async def get_chatroom_nickname(self, wxid: Union[str, list[str]], chatroom: str) -> Union[str, list[str]]:
+        """获取成员在群内的展示昵称。"""
+        members = await self.get_chatroom_member_list(chatroom)
+        member_map = {}
+        for member in members:
+            member_wxid = str(member.get("UserName", "") or "")
+            nickname = member.get("DisplayName") or member.get("NickName") or member_wxid
+            member_map[member_wxid] = nickname
+
+        if isinstance(wxid, str):
+            return str(member_map.get(wxid, ""))
+        return [str(member_map.get(single_wxid, "")) for single_wxid in wxid]
+
+    async def get_chatroom_member_detail(self, wxid: str, chatroom: str) -> dict:
+        """获取单个群成员详情。"""
+        members = await self.get_chatroom_member_list(chatroom)
+        for member in members:
+            if str(member.get("UserName", "") or "") == wxid:
+                return dict(member)
+        return {}