fix(layout): use the generic user icon (not login) for the logged-out menu trigger

The top-right menu trigger showed a LogIn (arrow-into-door) icon when
logged out; use the generic User icon instead — it reads as "your
account / profile" and matches the avatar shown when logged in. Still
opens the same profile/menu sheet (with the login CTA).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/components/layout/StandaloneMenu.vue

@@ -2,7 +2,7 @@
 import { ref, type Component } from 'vue'
 import { useI18n } from 'vue-i18n'
 import { useRouter } from 'vue-router'
-import { LogIn } from 'lucide-vue-next'
+import { User } from 'lucide-vue-next'
 import {
   Sheet,
   SheetContent,
@@ -62,7 +62,7 @@ function handleClick(item: SidebarNavItem) {
           <AvatarImage v-if="pictureUrl" :src="pictureUrl" :alt="displayName ?? ''" />
           <AvatarFallback>{{ fallbackInitial || '?' }}</AvatarFallback>
         </Avatar>
-        <LogIn v-else class="w-5 h-5" />
+        <User v-else class="w-5 h-5" />
       </button>
     </SheetTrigger>
     <SheetContent side="right" class="w-80 sm:w-96 max-w-full overflow-y-auto overflow-x-hidden">