style: resolve PR #80 review comments, standardize border variables, improve a11y & disposal

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

@@ -7,12 +7,12 @@
     {
         <div @key='"current-reading-book"' class="card-layout">
             <div class="book-cover">
-                <img src="@(string.IsNullOrEmpty(Book.CoverUrl) ? "https://via.placeholder.com/120x180?text=No+Cover" : Book.CoverUrl)" alt="@Book.Title" />
+                <img src="@(string.IsNullOrEmpty(Book.CoverUrl) ? "https://via.placeholder.com/120x180?text=No+Cover" : Book.CoverUrl)" alt="@Book.Title" aria-describedby="book-title-@Book.Id" />
             </div>
             
             <div class="book-details">
                 <div class="header-info">
-                    <h3 class="book-title">@Book.Title</h3>
+                    <h3 id="book-title-@Book.Id" class="book-title">@Book.Title</h3>
                     <span class="author-name">by @Book.Author.Name</span>
                 </div>
 
@@ -41,7 +41,7 @@
                 }
 
                 <div class="actions">
-                    <button class="btn-nexus outline" @onclick="HandleContinueReading">
+                    <button class="btn-nexus outline" @onclick="HandleContinueReading" aria-label="Kontynuuj czytanie">
                         Kontynuuj czytanie
                         <NexusIcon Name="arrow-right" Size="16" />
                     </button>