refactor: 统一使用现代类型注解替代传统类型注解

- 将 Dict、List 等传统类型注解替换为 dict、list 等现代类型注解
- 更新类型注解以更精确地反映变量类型
- 修复部分类型注解与实际使用不匹配的问题
- 优化部分代码逻辑以提高类型安全性

shared/protocol.py

@@ -16,9 +16,9 @@ class RegisterMessage:
     """Host client -> Router: Register this node."""
     type: str = "register"
     node_id: str = ""
-    serves_users: List[str] = field(default_factory=list)
+    serves_users: list[str] = field(default_factory=list)
     working_dir: str = ""
-    capabilities: List[str] = field(default_factory=list)
+    capabilities: list[str] = field(default_factory=list)
     display_name: str = ""
 
 
@@ -63,7 +63,7 @@ class NodeStatus:
     type: str = "node_status"
     node_id: str = ""
     sessions: int = 0
-    active_sessions: List[Dict[str, Any]] = field(default_factory=list)
+    active_sessions: list[dict[str, Any]] = field(default_factory=list)
 
 
 MESSAGE_TYPES = {