feat(clipping): implement hide/recover toggle for all section dialogs

Update all three section dialogs to support hide/show toggle:

SectionAxisDialogManager:
- onHideToggle now calls hideSection()/recoverSection()

SectionBoxDialogManager:
- onHideToggle now calls hideSection()/recoverSection()

SectionPlanePanel:
- Add isHidden state tracking
- Change onHide to onHideToggle(isHidden)
- Add setHiddenState/getHiddenState methods
- Update button to toggle active state

SectionPlaneDialogManager:
- Switch to onHideToggle callback
- Call hideSection()/recoverSection() based on toggle state

Behavior: Click hide button to hide section, click again to recover.

demo/index.html

@@ -6,7 +6,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>iFlow Engine Demo</title>
     <!-- 从本地 lib 目录加载 SDK 文件 -->
-    <script src="../dist/iflow-engine.umd.js"></script>
+    <script src="./lib/iflow-engine.umd.js"></script>
     <style>
         * {
             box-sizing: border-box;