feat(reader): convert reading progress indicator to Tailwind

- Replace CSS classes with Tailwind utilities
- Use gradient backgrounds with conditional colors
- Add shimmer animation to Tailwind config
- Remove 80+ lines of CSS from reader.css
- Maintain z-index layering (1102) above mobile overlays
- Responsive design with utility classes

src/components/ReadingProgressIndicator.tsx

@@ -13,17 +13,27 @@ export const ReadingProgressIndicator: React.FC<ReadingProgressIndicatorProps> =
   showPercentage = true,
   className = ''
 }) => {
+  const clampedProgress = Math.min(100, Math.max(0, progress))
+  
   return (
-    <div className={`reading-progress-indicator ${className}`}>
-      <div className="reading-progress-bar">
+    <div className={`fixed bottom-0 left-0 right-0 z-[1102] bg-[rgba(26,26,26,0.95)] backdrop-blur-md border-t border-white/10 px-4 py-2 flex items-center gap-4 transition-all duration-300 shadow-[0_-4px_12px_rgba(0,0,0,0.3)] ${className}`}>
+      <div className="flex-1 h-1 bg-white/10 rounded-sm overflow-hidden relative">
         <div 
-          className={`reading-progress-fill ${isComplete ? 'complete' : ''}`}
-          style={{ width: `${Math.min(100, Math.max(0, progress))}%` }}
-        />
+          className={`h-full rounded-sm transition-all duration-300 relative ${
+            isComplete 
+              ? 'bg-gradient-to-r from-green-400 to-green-600' 
+              : 'bg-gradient-to-r from-indigo-500 to-blue-400'
+          }`}
+          style={{ width: `${clampedProgress}%` }}
+        >
+          <div className="absolute inset-0 bg-gradient-to-r from-transparent via-white/30 to-transparent animate-[shimmer_2s_infinite]" />
+        </div>
       </div>
       {showPercentage && (
-        <div className="reading-progress-text">
-          {isComplete ? '✓ Complete' : `${progress}%`}
+        <div className={`text-sm font-medium min-w-[80px] text-right ${
+          isComplete ? 'text-green-400' : 'text-gray-400'
+        }`}>
+          {isComplete ? '✓ Complete' : `${clampedProgress}%`}
         </div>
       )}
     </div>