feat: Add buffering indicator and improve queue item removal

Introduces a visual indicator for when the reader is buffering, meaning it's supposed to be playing but the current audio segment is not yet available.

Also, prevents accidental article selection when clicking the "Remove" button in the queue by adding `stopPropagation`.

components/ReaderView.tsx

@@ -106,6 +106,8 @@ export const ReaderView: React.FC<ReaderViewProps> = ({ article, settings, onTog
         {article.segments.length > 0 ? (
           article.segments.map((segment, idx) => {
             const isActive = article.currentSegmentIndex === idx;
+            const isBuffering = isActive && article.status === 'PLAYING' && !segment.audioUrl;
+
             return (
               <div 
                 key={segment.id} 
@@ -116,7 +118,7 @@ export const ReaderView: React.FC<ReaderViewProps> = ({ article, settings, onTog
                   transition-all duration-200 whitespace-pre-wrap rounded-xl p-3 sm:p-4 -mx-2 sm:-mx-4 border-l-4 mb-2
                   ${getLeadingClass()}
                   ${isActive 
-                    ? 'text-slate-900 dark:text-white bg-blue-50 dark:bg-blue-900/20 border-blue-500 shadow-sm' 
+                    ? `bg-blue-50 dark:bg-blue-900/20 border-blue-500 shadow-sm ${isBuffering ? 'animate-pulse opacity-70' : 'text-slate-900 dark:text-white'}` 
                     : 'text-slate-700 dark:text-slate-300 border-transparent hover:bg-slate-100 dark:hover:bg-slate-800/50 cursor-pointer hover:border-slate-300 dark:hover:border-slate-600'
                   }
                 `}