feat(user): add local avatar management flow

assets/admin/src/pages/SiteSettings.vue

@@ -85,22 +85,6 @@
         </n-form>
       </n-card>
 
-      <!-- 4. 头像 -->
-      <n-card class="aksrt-section-card">
-        <div class="aksrt-section-header">
-          <span class="section-icon"><svg xmlns="http://www.w3.org/2000/svg" width="17" height="17" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M20 21v-2a4 4 0 0 0-4-4H8a4 4 0 0 0-4 4v2"/><circle cx="12" cy="7" r="4"/></svg></span>
-          <h3>Gravatar 头像源</h3>
-        </div>
-        <n-form :model="basic" label-placement="left" label-width="130" class="aksrt-form">
-          <n-form-item label="头像服务源">
-            <n-select v-model:value="basic.avatar_source" :options="avatarSourceOptions" placeholder="选择头像镜像源" />
-            <template #feedback>
-              <span class="aksrt-hint-text">国内站点建议优先选 Cravatar。</span>
-            </template>
-          </n-form-item>
-        </n-form>
-      </n-card>
-
       <!-- 5. 备案 -->
       <n-card class="aksrt-section-card">
         <div class="aksrt-section-header">
@@ -140,7 +124,6 @@ const saving = ref(false)
 const basic = reactive({
   comment_enabled: true,
   comment_requires_registration: false,
-  avatar_source: 'cn.cravatar.com',
   icp_number: '',
   police_number: '',
   lazyload_enabled: true,
@@ -149,12 +132,6 @@ const basic = reactive({
   comment_pagination_mode: 'numbered',
 })
 
-const avatarSourceOptions = [
-  { label: 'Cravatar (国内推荐)', value: 'cn.cravatar.com' },
-  { label: 'Gravatar 国内镜像', value: 'cn.gravatar.com' },
-  { label: 'Gravatar 官方', value: 'gravatar.com' },
-]
-
 async function loadAll() {
   loading.value = true
   try {
@@ -163,7 +140,6 @@ async function loadAll() {
       const d = basicRes.data
       basic.comment_enabled = d.comment_enabled !== false
       basic.comment_requires_registration = !!d.comment_requires_registration
-      basic.avatar_source = d.avatar_source || 'cn.cravatar.com'
       basic.icp_number = d.icp_number || ''
       basic.police_number = d.police_number || ''
       basic.lazyload_enabled = d.lazyload_enabled !== false
@@ -184,7 +160,6 @@ async function handleSave() {
     const basicPayload = {
       comment_enabled: basic.comment_enabled,
       comment_requires_registration: basic.comment_requires_registration,
-      avatar_source: basic.avatar_source,
       icp_number: basic.icp_number,
       police_number: basic.police_number,
       lazyload_enabled: basic.lazyload_enabled,