Enhance UI components and styles for better performance and accessibility

- Added a fixed minimum height to the AdSlot component to reduce Cumulative Layout Shift (CLS) and adjusted styles for better layout consistency.
- Specified width and height attributes for the Barcode and QR Code images to improve rendering performance and maintain aspect ratios.
- Introduced font-face declarations in global CSS for 'Inter' and 'Tajawal' fonts with 'swap' display to optimize font loading and reduce CLS.

frontend/src/styles/global.css

@@ -29,6 +29,22 @@
     text-rendering: optimizeLegibility;
   }
 
+  /* تحسين تحميل الخطوط لتقليل CLS */
+  @font-face {
+    font-family: 'Inter';
+    font-style: normal;
+    font-weight: 400;
+    src: local('Inter'), url('/fonts/Inter.woff2') format('woff2');
+    font-display: swap;
+  }
+  @font-face {
+    font-family: 'Tajawal';
+    font-style: normal;
+    font-weight: 400;
+    src: local('Tajawal'), url('/fonts/Tajawal.woff2') format('woff2');
+    font-display: swap;
+  }
+
   /* RTL Support */
   [dir="rtl"] body {
     font-family: 'Tajawal', 'Inter', system-ui, sans-serif;