完善后台接口字段

frontend-vue/src/pages/brand/components/BrandProductRiskTab.vue

@@ -37,6 +37,7 @@
         <div class="country-pref-checks">
           <label v-for="row in countryCheckboxRows" :key="row.code" class="country-check-row">
             <input type="checkbox" class="country-check-input" :checked="isCountrySelected(row.code)"
+              :disabled="isCountrySelectionLocked(row.code)"
               @change="onCountryNativeChange(row.code, $event)" />
             <span class="country-check-text">{{ row.label }}（{{ row.code }}）</span>
           </label>
@@ -278,9 +279,18 @@ function isCountrySelected(code: string) {
   return orderedCountryCodes.value.includes(code)
 }
 
+function isCountrySelectionLocked(code: string) {
+  return orderedCountryCodes.value.length === 1 && orderedCountryCodes.value[0] === code
+}
+
 function onCountryNativeChange(code: string, e: Event) {
   const el = e.target as HTMLInputElement | null
   if (!el) return
+  if (!el.checked && isCountrySelectionLocked(code)) {
+    el.checked = true
+    ElMessage.warning('至少保留 1 个国家')
+    return
+  }
   onCountryToggle(code, el.checked)
 }