fix: give .home explicit height so flex children resolve correctly

On Chrome Android, cross-axis stretch doesn't always produce a
definite height for inner flex items. Adding height: 100dvh to
.home ensures flex: 1 on .welcome-world resolves to full viewport.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/views/HomeApp.vue

@@ -16,6 +16,7 @@ import WelcomeWorld from "@/components/WelcomeWorld.vue"
   flex: 1;
   flex-direction: column;
   align-items: center;
+  height: 100dvh;
 }
 
 .authorize {