feat: implement draggable sidebar resizer with persistent state and dynamic UI updates

src/NexusReader.UI.Shared/Layout/MainLayout.razor

@@ -6,6 +6,7 @@
 @inject IPlatformService PlatformService
 @inject IFocusModeService FocusMode
 @inject IQuizStateService QuizService
+@inject IJSRuntime JS
 @implements IDisposable
 
 <div class="app-container @_platformClass @(FocusMode.IsFocusModeActive ? "focus-mode-active" : "")">
@@ -16,6 +17,8 @@
         <ReaderFooter />
     </div>
 
+    <div class="resizer" id="sidebar-resizer"></div>
+
     <div class="intelligence-sidebar">
         <IntelligenceToolbar />
         <div class="intelligence-content">
@@ -58,6 +61,19 @@
         }
     }
 
+    protected override async Task OnAfterRenderAsync(bool firstRender)
+    {
+        if (firstRender)
+        {
+            try
+            {
+                var module = await JS.InvokeAsync<IJSObjectReference>("import", "./_content/NexusReader.UI.Shared/js/layoutResizer.js");
+                await module.InvokeVoidAsync("initResizer", ".app-container", "#sidebar-resizer", "--sidebar-width");
+            }
+            catch { }
+        }
+    }
+
     public void Dispose()
     {
         FocusMode.OnFocusModeChanged -= StateHasChanged;