fix : reset sidebar state on logout

Add resetSidebar() to useSidebar composable and call it on logout
to prevent stale sidebar data after re-login.

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

frontend/modules/core/pages/logout.vue

@@ -8,9 +8,11 @@
 definePageMeta({ layout: 'auth' })
 
 const auth = useAuthStore()
+const { resetSidebar } = useSidebar()
 
 onMounted(async () => {
     await auth.logout()
+    resetSidebar()
     await navigateTo('/login')
 })
 </script>