Refactor IntroText component for improved readability and add italic font style for Nunito

Update favicon and app icons for better visual consistency

src/lib/components/IntroText.svelte

@@ -1,9 +1,9 @@
 <section class="intro" aria-labelledby="intro-title">
   <h2 id="intro-title" class="sr-only">About Squiggleverse</h2>
   <p>
-    Squiggleverse is a modular, multi-platform, game-based “stealth” learning system that teaches
-    grammar, usage, and style through innovative gameplay, whimsical characters, and creative
-    narratives co-authored by the player.
+    <em>Squiggleverse</em> is a modular, multi-platform, game-based “stealth” learning system that
+    teaches grammar, usage, and style through innovative gameplay, whimsical characters, and
+    creative narratives co-authored by the player.
   </p>
   <div class="star-divider" aria-hidden="true">
     <span></span>

src/routes/+layout.svelte

@@ -1,5 +1,6 @@
 <script lang="ts">
   import '@fontsource/nunito/latin-500.css';
+  import '@fontsource/nunito/latin-500-italic.css';
   import '../app.css';
 
   let { children } = $props();