fix: SettingsView owner→canManageUsers (owner || admin)

Vorher war isOwner (= nur owner) gesetzt, was admins die User-Verwaltung
verweigerte. Jetzt: canManageUsers = role===owner || role===admin.

Delta: 1 Datei, 4 Zeilen (2 Logic, 1 Kommentar, 1 v-if).
Builds: Backend 0 Errors, Frontend 0 Errors.

frontend/src/views/SettingsView.vue

@@ -125,10 +125,10 @@ const creatingUser = ref(false)
 const createError = ref('')
 const createSuccess = ref('')
 
-const isOwner = auth.user?.role === 'owner'
+const canManageUsers = auth.user?.role === 'owner' || auth.user?.role === 'admin'
 
 async function loadUsers() {
-  if (!isOwner) return
+  if (!canManageUsers) return
   usersLoading.value = true
   usersError.value = ''
   try {
@@ -292,8 +292,8 @@ onMounted(() => {
         </form>
       </section>
 
-      <!-- ── Admin: User Management (only owner) ── -->
+      <!-- ── Admin: User Management (owner & admin) ── -->
-      <section v-if="isOwner" class="glass-card admin-card">
+      <section v-if="canManageUsers" class="glass-card admin-card">
         <div class="card-head">
           <Shield :size="18" />
           <h2>Benutzerverwaltung</h2>