fix: add validation rules for group selection in FormBasicInfoAgencies component

src/components/07_agencies-management/FormBasicInfoAgencies.vue

@@ -46,6 +46,7 @@ type Options = { label: string; value: string };
             (lhs: Options, rhs: Options) => lhs.value.localeCompare(rhs.value),
           )
         "
+        :rules="[(val: string) => !!val || $t('form.error.required')]"
         v-model="group"
       >
         <template v-slot:option="{ scope, opt }">