feat: implement epub service, navigation service, and global error boundary with updated reader UI layouts

src/NexusReader.UI.Shared/Components/Organisms/ReaderCanvas.razor

@@ -7,13 +7,14 @@
 @inject IJSRuntime JS
 @inject IThemeService ThemeService
 @inject IFocusModeService FocusMode
+@inject IReaderNavigationService NavigationService
 
-<div class="reader-canvas theme-light">
-
-
+<div class="reader-canvas @(ThemeService.IsLightMode ? "theme-light" : "theme-dark")">
     @if (ViewModel == null)
     {
-        <NexusTypography Variant="NexusTypography.TypographyVariant.UI">@StatusMessage</NexusTypography>
+        <div class="loading-state">
+            <NexusTypography Variant="NexusTypography.TypographyVariant.UI">@StatusMessage</NexusTypography>
+        </div>
     }
     else
     {
@@ -23,7 +24,7 @@
                 <div id="@block.Id" class="block-wrapper">
                     @if (block is TextSegmentBlock textSegment)
                     {
-                        <NexusTypography Variant="NexusTypography.TypographyVariant.Ebook">@textSegment.Content</NexusTypography>
+                        <NexusTypography Variant="NexusTypography.TypographyVariant.Ebook">@((MarkupString)textSegment.Content)</NexusTypography>
                     }
                     else if (block is AiActionTriggerBlock aiTrigger)
                     {
@@ -43,18 +44,37 @@
     private ReaderPageViewModel? ViewModel;
     private string StatusMessage = "Loading chapter...";
 
-    protected override async Task OnInitializedAsync()
+    protected override void OnInitialized()
     {
         ThemeService.OnThemeChanged += StateHasChanged;
+        NavigationService.OnNavigationChanged += OnNavigationChanged;
+    }
 
-        var result = await Mediator.Send(new GetReaderPageQuery());
+    protected override async Task OnParametersSetAsync()
+    {
+        await LoadChapterAsync(NavigationService.CurrentChapterIndex);
+    }
+
+    private async void OnNavigationChanged()
+    {
+        await LoadChapterAsync(NavigationService.CurrentChapterIndex);
+        StateHasChanged();
+    }
+
+    private async Task LoadChapterAsync(int index)
+    {
+        ViewModel = null;
+        StatusMessage = "Fetching content...";
+        
+        var result = await Mediator.Send(new GetReaderPageQuery(index));
         if (result.IsSuccess)
         {
             ViewModel = result.Value;
+            NavigationService.UpdateMetadata(ViewModel.CurrentChapterIndex, ViewModel.TotalChapters, ViewModel.ChapterTitle);
         }
         else
         {
-            StatusMessage = "Failed to load chapter content.";
+            StatusMessage = $"Error: {result.Errors.FirstOrDefault()?.Message ?? "Failed to load"}";
         }
     }
 
@@ -75,5 +95,6 @@
     public void Dispose()
     {
         ThemeService.OnThemeChanged -= StateHasChanged;
+        NavigationService.OnNavigationChanged -= OnNavigationChanged;
     }
 }