refactor: handle rules last name

src/components/02_personnel-management/FormPerson.vue

@@ -221,7 +221,6 @@ watch(
           class="col"
           :label="$t('personnel.form.lastName')"
           v-model="lastName"
-          :rules="[(val: string) => !!val || $t('form.error.required')]"
         />
       </div>
 
@@ -289,9 +288,8 @@ watch(
           label="Surname"
           v-model="lastNameEN"
           :rules="[
-            (val: string) => !!val || $t('form.error.required'),
             (val: string) =>
-              /^[A-Za-z\s]+$/.test(val) || $t('form.error.letterOnly'),
+              !val || /^[A-Za-z\s]+$/.test(val) || $t('form.error.letterOnly'),
           ]"
         />
       </div>