feat(services): add Service Types management UI

Admin CRUD page for service types, plus wiring the student "request
service" form's category select to the real list instead of a
hardcoded pair of options.

src/layouts/AdminLayout.vue

@@ -147,8 +147,19 @@ const menuItems = computed(() => [
   {
     title: 'مدیریت خدمات',
     icon: 'users-three',
-    to: { name: 'admin-services' },
-    active: route.name === 'admin-services',
+    active: ['admin-services', 'admin-service-types'].includes(route.name),
+    children: [
+      {
+        title: 'درخواست‌های خدمت',
+        to: { name: 'admin-services' },
+        active: route.name === 'admin-services',
+      },
+      {
+        title: 'انواع خدمات',
+        to: { name: 'admin-service-types' },
+        active: route.name === 'admin-service-types',
+      },
+    ],
   },
   {
     title: 'مدیریت مشاوره',