Migrate frontend from Alpine.js to SvelteKit and update documentation

Migrated the frontend from Alpine.js to SvelteKit with shared UI stores.
Updated the project structure to use SvelteKit primitives for routing,
state management, and form handling. Added a new round counter component
and updated the project root to use a single Dockerfile. Updated
dependencies including Alpine.js, Vite, and SvelteKit. Refined CSS and
configuration files for the new frontend stack.

frontend/static/css/styles.css

@@ -1,6 +1,6 @@
 @import url('https://fonts.googleapis.com/css2?family=Cinzel:wght@400;700&family=Inter:wght@300;400;500;600;700&display=swap');
 
-/* Alpine.js x-cloak - hide elements until Alpine initializes */
+/* Utility to hide elements until JS initializes */
 [x-cloak] {
   display: none !important;
 }