Add initial project setup with static files and configuration

- Create robots.txt to allow all user agents and specify sitemap location
- Add site.webmanifest for PWA support with app details
- Initialize sitemap.xml with the homepage URL and metadata
- Set up svelte.config.js for SvelteKit with static adapter and prerendering
- Configure TypeScript with tsconfig.json for strict type checking and module resolution
- Establish Vite configuration in vite.config.ts for SvelteKit integration

src/lib/components/IntroText.svelte

@@ -0,0 +1,8 @@
+<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.
+  </p>
+</section>