refactor(autoscript): 对象化 ASEngine、移除旧变量导出、清理编排窗口解析逻辑

- ASEngine 转为类，目标变量注册作为 __init__ 接口，配套函数提取到 _helpers.py
- Lua 函数重命名 CURRENT_DATE→datenow, CURRENT_TIME→timenow, date_add→dateadd 等
- __init__.py 移除 ALL_VARIABLES/_TARGET_VAR_DEFS/_MOCK_TYPE_VALUES 导出，替换为接口函数
- 编排窗口移除脚本→控件的反向解析逻辑，合并常量定义为查询接口
- 编辑窗口新增工具函数 Tab、Tab 键插入 4 空格、图标改用 setIcon 加载

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/gui/ALWebDriverDownloadDialog.py

@@ -31,7 +31,7 @@ from PySide6.QtWidgets import (
 from PySide6.QtGui import QCloseEvent
 
 from managers.driver.WebDriverManager import (
-    instance as webdriverManagerInstance,
+    instance as webdriverInstance,
     WebDriverManager,
     WebDriverInfo,
     WebDriverType,
@@ -261,7 +261,7 @@ class ALWebDriverDownloadDialog(QDialog):
     ):
 
         try:
-            self.__driver_manager = webdriverManagerInstance(self.__driver_dir)
+            self.__driver_manager = webdriverInstance(self.__driver_dir)
         except ValueError as e:
             QMessageBox.warning(self, "初始化失败", f"WebDriverManager 初始化失败:\n{str(e)}")
             self.reject()