feat(avatar) : replace initials with UserAvatar component everywhere

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

frontend/components/ui/AppTopNav.vue

@@ -10,12 +10,14 @@
       <div class="ml-auto flex items-center gap-4 text-xl text-white sm:gap-8">
         <NotificationBell />
         <div class="group relative flex gap-2 sm:gap-4">
-          <Icon name="mdi:account-circle-outline" class="self-center cursor-pointer" size="36" />
+          <UserAvatar v-if="user" :user="user" size="md" class="cursor-pointer" />
+          <Icon v-else name="mdi:account-circle-outline" class="self-center cursor-pointer" size="36" />
           <p class="hidden self-center cursor-pointer sm:block">{{ user?.username }}</p>
           <div class="invisible absolute right-0 top-full z-50 mt-2 w-44 rounded-md border border-neutral-200 bg-white py-1 text-sm text-neutral-800 opacity-0 shadow-lg transition-all group-hover:visible group-hover:opacity-100">
             <button
               type="button"
               class="block w-full px-3 py-2 text-left hover:bg-neutral-100"
+              @click="navigateTo('/profile')"
             >
               Mon profil
             </button>
@@ -43,7 +45,7 @@ defineProps<{
 const auth = useAuthStore()
 const ui = useUiStore()
 
-const handleLogout = async () => {
+async function handleLogout() {
   await auth.logout()
   await navigateTo('/login')
 }