CLAUDE: Fix Nuxt 4 store import in game layout

Add explicit Pinia store imports to layouts/game.vue. Nuxt 4 requires
explicit imports for stores - auto-imports no longer work.

This fixes: ReferenceError: useAuthStore is not defined

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend-sba/layouts/game.vue

@@ -66,6 +66,9 @@
 </template>
 
 <script setup lang="ts">
+import { useAuthStore } from '~/store/auth'
+import { useGameStore } from '~/store/game'
+
 const authStore = useAuthStore()
 const gameStore = useGameStore()