feat(kon): add semantic HTML and ARIA labels — main wrapper, live regions, button labels

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/routes/+page.svelte

@@ -13,7 +13,7 @@
   });
 </script>
 
-<div class="h-full overflow-hidden">
+<main class="h-full overflow-hidden" aria-label="Kon application content">
   {#if page.current === "first-run"}
     <FirstRunPage />
   {:else if page.current === "dictation"}
@@ -27,4 +27,4 @@
   {:else if page.current === "settings"}
     <SettingsPage />
   {/if}
-</div>
+</main>