Add WebGL book scene checkpoint

public/js/ui-display-handler-module.js

@@ -11,7 +11,7 @@ class UIDisplayHandlerModule extends BaseModule {
         super('ui-display-handler', 'UI Display Handler');
         
         // Module dependencies
-        this.dependencies = ['layout-renderer', 'playback-coordinator', 'game-config', 'localization', 'story-history', 'sentence-queue', 'persistence-manager', 'markup-parser'];
+        this.dependencies = ['layout-renderer', 'webgl-book-scene', 'playback-coordinator', 'game-config', 'localization', 'story-history', 'sentence-queue', 'persistence-manager', 'markup-parser'];
         
         // DOM elements
         this.container = null;
@@ -170,6 +170,7 @@ class UIDisplayHandlerModule extends BaseModule {
             
             // Get references to required modules using parent's getModule method
             this.layoutRenderer = this.getModule('layout-renderer');
+            this.webglBookScene = this.getModule('webgl-book-scene');
             this.playbackCoordinator = this.getModule('playback-coordinator');
             this.gameConfig = this.getModule('game-config');
             this.localization = this.getModule('localization');
@@ -355,6 +356,8 @@ class UIDisplayHandlerModule extends BaseModule {
      * Initialize the UI containers
      */
     initializeContainers() {
+        this.webglBookScene?.ensureShell?.();
+
         // Check if the book container already exists
         let bookContainer = document.getElementById('book');
         if (!bookContainer) {
@@ -526,7 +529,10 @@ class UIDisplayHandlerModule extends BaseModule {
         this.createNotificationDialog();
         
         console.log('UIDisplayHandler: All containers initialized');
+        this.webglBookScene?.adoptPageContent?.();
+        this.webglBookScene?.refreshModalOverview?.();
         this.applyGameConfig(this.gameConfig?.getConfig?.());
+        this.webglBookScene?.adoptPageContent?.();
         this.applyTranslations();
         this.measureStoryLineHeight();
         this.setStoryOffset(0);