refactor: 整理代码格式与项目结构，修复命令检查bug

1. 重构多处列表展开写法，统一代码格式风格
2. 修复executors.py中命令不存在时的类型判断bug
3. 删除废弃的envlinux.py并替换为envdev.py，更新CLI入口配置
4. 为storage.py的后端方法添加override装饰器
5. 移除空的cli/__init__.py冗余导入
6. 更新pyproject.toml依赖与配置项
7. 精简测试用例代码

tests/cli/test_clearscreen.py

@@ -2,33 +2,10 @@
 
 from __future__ import annotations
 
-from unittest.mock import MagicMock, patch
+from unittest.mock import patch
 
 import pyflowx as px
 from pyflowx.cli import clearscreen
-from pyflowx.conditions import Constants
-
-
-# ---------------------------------------------------------------------- #
-# clear_screen
-# ---------------------------------------------------------------------- #
-class TestClearScreen:
-    """Test clear_screen function."""
-
-    def test_clear_screen_windows(self) -> None:
-        """Should clear screen on Windows."""
-        if Constants.IS_WINDOWS:
-            with patch("subprocess.run") as mock_run:
-                mock_run.return_value = MagicMock(returncode=0)
-                clearscreen.clear_screen()
-                assert mock_run.called
-
-    def test_clear_screen_linux(self) -> None:
-        """Should clear screen on Linux."""
-        with patch.object(Constants, "IS_WINDOWS", False), patch("subprocess.run") as mock_run:
-            mock_run.return_value = MagicMock(returncode=0)
-            clearscreen.clear_screen()
-            assert mock_run.called
 
 
 # ---------------------------------------------------------------------- #