让 Robot 接入 WechatGateway 并同步推进文档

- 为 WechatGateway 增加属性写透传，兼容现有 ipad_bot 属性赋值方式
- 将 Robot 的 wechat 接入实例化入口切换为 Gateway，并默认走 legacy_855 provider
- 在适配路线图中补充当前推进状态，明确已完成项与待迁移运行时职责

wechat_ipad/gateway.py

@@ -17,6 +17,7 @@ class WechatGateway:
         "855": Legacy855WechatClient,
         "859": Legacy855WechatClient,
     }
+    _LOCAL_ATTRS = {"server_type", "provider"}
 
     def __init__(self, ip: str, port: int, server_type: str = "legacy_855", **kwargs: Any):
         normalized_server_type = str(server_type or "legacy_855").strip().lower()
@@ -24,10 +25,16 @@ class WechatGateway:
         if provider_cls is None:
             raise ValueError(f"不支持的 wechat provider 类型: {server_type}")
 
-        self.server_type = normalized_server_type
-        self.provider = provider_cls(ip=ip, port=port, **kwargs)
+        object.__setattr__(self, "server_type", normalized_server_type)
+        object.__setattr__(self, "provider", provider_cls(ip=ip, port=port, **kwargs))
 
     def __getattr__(self, item: str) -> Any:
         """将未显式实现的属性/方法透传给具体 Provider。"""
         return getattr(self.provider, item)
 
+    def __setattr__(self, key: str, value: Any) -> None:
+        """将运行期动态属性写入透传给 Provider，保持旧调用面的兼容性。"""
+        if key in self._LOCAL_ATTRS or "provider" not in self.__dict__:
+            object.__setattr__(self, key, value)
+            return
+        setattr(self.provider, key, value)