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/resources/icons/Copy.svg

@@ -0,0 +1,6 @@
+<svg width="24" height="24" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg">
+  <path d="M13 7H7V5H13V7Z" fill="currentColor"/>
+  <path d="M13 11H7V9H13V11Z" fill="currentColor"/>
+  <path d="M7 15H13V13H7V15Z" fill="currentColor"/>
+  <path fill-rule="evenodd" clip-rule="evenodd" d="M3 19V1H17V5H21V23H7V19H3ZM15 17V3H5V17H15ZM17 7V19H9V21H19V7H17Z" fill="currentColor"/>
+</svg>

src/gui/resources/icons/Reset.svg

@@ -0,0 +1,3 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="currentColor">
+  <path d="M20.817 11.186a8.94 8.94 0 0 0-1.355-3.219 9.053 9.053 0 0 0-2.43-2.43 8.95 8.95 0 0 0-3.219-1.355 9.028 9.028 0 0 0-1.838-.18V2L8 5l3.975 3V6.002c.484-.002.968.044 1.435.14a6.961 6.961 0 0 1 2.502 1.053 7.005 7.005 0 0 1 1.892 1.892A6.967 6.967 0 0 1 19 13a7.032 7.032 0 0 1-.55 2.725 7.11 7.11 0 0 1-.644 1.188 7.2 7.2 0 0 1-.858 1.039 7.028 7.028 0 0 1-3.536 1.907 7.13 7.13 0 0 1-2.822 0 6.961 6.961 0 0 1-2.503-1.054 7.002 7.002 0 0 1-1.89-1.89A6.996 6.996 0 0 1 5 13H3a9.02 9.02 0 0 0 1.539 5.034 9.096 9.096 0 0 0 2.428 2.428A8.95 8.95 0 0 0 12 22a9.09 9.09 0 0 0 1.814-.183 9.014 9.014 0 0 0 3.218-1.355 8.886 8.886 0 0 0 1.331-1.099 9.228 9.228 0 0 0 1.1-1.332A8.952 8.952 0 0 0 21 13a9.09 9.09 0 0 0-.183-1.814z" fill="currentColor"/>
+</svg>