feat: add meta description

src/app/ui/Layout.svelte

@@ -73,6 +73,10 @@ onDestroy(() => themeManager.destroy());
         />
     </noscript>
     <title>GlyphDiff | Typography & Typefaces</title>
+    <meta
+        name="description"
+        content="Compare typefaces side by side. Adjust size, weight, leading, and tracking to find the perfect typographic pairing."
+    />
 </svelte:head>
 
 <ResponsiveProvider>