feat: 实现多主机架构的核心组件

新增路由器、主机客户端和共享协议模块，支持多主机部署模式：
- 路由器作为中央节点管理主机连接和消息路由
- 主机客户端作为工作节点运行本地代理
- 共享协议定义通信消息格式
- 新增独立运行模式standalone.py
- 更新配置系统支持路由模式

shared/__init__.py

@@ -0,0 +1,23 @@
+"""Shared module for Router <-> Host Client communication."""
+
+from shared.protocol import (
+    RegisterMessage,
+    ForwardRequest,
+    ForwardResponse,
+    TaskComplete,
+    Heartbeat,
+    NodeStatus,
+    encode,
+    decode,
+)
+
+__all__ = [
+    "RegisterMessage",
+    "ForwardRequest",
+    "ForwardResponse",
+    "TaskComplete",
+    "Heartbeat",
+    "NodeStatus",
+    "encode",
+    "decode",
+]

shared/protocol.py

@@ -0,0 +1,94 @@
+"""Shared protocol module for Router <-> Host Client communication.
+
+All message types are dataclasses that serialize to/from JSON.
+Both router and host client import from this module.
+"""
+
+from __future__ import annotations
+
+import json
+from dataclasses import asdict, dataclass, field
+from typing import Any, Dict, List, Optional
+
+
+@dataclass
+class RegisterMessage:
+    """Host client -> Router: Register this node."""
+    type: str = "register"
+    node_id: str = ""
+    serves_users: List[str] = field(default_factory=list)
+    working_dir: str = ""
+    capabilities: List[str] = field(default_factory=list)
+    display_name: str = ""
+
+
+@dataclass
+class ForwardRequest:
+    """Router -> Host client: Forward a user message."""
+    type: str = "forward"
+    id: str = ""
+    user_id: str = ""
+    chat_id: str = ""
+    text: str = ""
+
+
+@dataclass
+class ForwardResponse:
+    """Host client -> Router: Reply to a forwarded message."""
+    type: str = "forward_response"
+    id: str = ""
+    reply: str = ""
+    error: str = ""
+
+
+@dataclass
+class TaskComplete:
+    """Host client -> Router: Background task finished."""
+    type: str = "task_complete"
+    task_id: str = ""
+    user_id: str = ""
+    chat_id: str = ""
+    result: str = ""
+
+
+@dataclass
+class Heartbeat:
+    """Bidirectional ping/pong."""
+    type: str = "ping"
+
+
+@dataclass
+class NodeStatus:
+    """Host client -> Router: Periodic status update."""
+    type: str = "node_status"
+    node_id: str = ""
+    sessions: int = 0
+    active_sessions: List[Dict[str, Any]] = field(default_factory=list)
+
+
+MESSAGE_TYPES = {
+    "register": RegisterMessage,
+    "forward": ForwardRequest,
+    "forward_response": ForwardResponse,
+    "task_complete": TaskComplete,
+    "ping": Heartbeat,
+    "pong": Heartbeat,
+    "node_status": NodeStatus,
+}
+
+
+def encode(msg: Any) -> str:
+    """Encode a message to JSON string."""
+    if hasattr(msg, "type"):
+        return json.dumps(asdict(msg), ensure_ascii=False)
+    raise ValueError(f"Invalid message type: {type(msg)}")
+
+
+def decode(data: str) -> Any:
+    """Decode a JSON string to a message object."""
+    obj = json.loads(data)
+    msg_type = obj.get("type")
+    if msg_type not in MESSAGE_TYPES:
+        raise ValueError(f"Unknown message type: {msg_type}")
+    cls = MESSAGE_TYPES[msg_type]
+    return cls(**{k: v for k, v in obj.items() if k in cls.__dataclass_fields__})