完善图片画布撤销保护与操作提示 (#89)

为画布历史记录补充操作类型和内容消失保护

增加撤销成功、恢复成功及阻止提示并在三秒后隐藏

补充拖动、上传、生成和替换等操作的历史语义

保留恢复按钮、Ctrl+Shift+Z 快捷键和双向历史栈

补充撤销与恢复规则的定向测试和说明文档

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Co-authored-by: 段舒康 <kdletters@qq.com>
Co-authored-by: kdletters <kdletters@qq.com>
Reviewed-on: https://git.genarrative.world/git/GenarrativeAI/Genarrative/pulls/89
Co-authored-by: oj-afraid-student <1373241747@qq.com>
Co-committed-by: oj-afraid-student <1373241747@qq.com>

src/index.css

@@ -5044,6 +5044,16 @@ html[data-mobile-keyboard-open='true'] .platform-mobile-bottom-dock {
   cursor: grab;
 }
 
+.image-canvas-editor__undo-toast {
+  position: absolute;
+  top: 1rem;
+  left: 50%;
+  z-index: 73;
+  max-width: min(32rem, calc(100% - 2rem));
+  transform: translateX(-50%);
+  pointer-events: none;
+}
+
 .image-canvas-editor__world {
   position: absolute;
   left: 0;