feat: 使用微信原生chooseAvatar获取头像

改用 button open-type="chooseAvatar" 替代上传方案，用户只能选择
微信头像，确保头像来源安全可控。头像URL直接存储到数据库。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/app/src/pages/profile/info.vue

@@ -2,6 +2,7 @@
   <view class="info-page">
     <!-- Avatar section -->
     <view class="avatar-section">
+      <button class="avatar-btn" open-type="chooseAvatar" @chooseavatar="handleChooseAvatar">
         <view class="avatar-wrap">
           <image
             v-if="avatarUrl"
@@ -13,6 +14,7 @@
             <text class="avatar-placeholder-text">{{ nicknameInitial }}</text>
           </view>
         </view>
+      </button>
       <text class="avatar-name">{{ form.nickname || '未设置昵称' }}</text>
       <text class="avatar-hint">微信头像</text>
     </view>
@@ -91,6 +93,7 @@ const form = ref({
 })
 const originalNickname = ref('')
 const saving = ref(false)
+const uploadingAvatar = ref(false)
 
 // ─── Computed ─────────────────────────────────────────────
 const isDirty = computed(() => form.value.nickname.trim() !== originalNickname.value)
@@ -122,6 +125,24 @@ const activeMembershipCount = computed(
   () => userStore.user?.activeMembershipCount ?? userStore.activeMemberships.length,
 )
 
+// ─── Avatar upload ────────────────────────────────────────
+async function handleChooseAvatar(e: { detail: { avatarUrl: string } }) {
+  const { avatarUrl } = e.detail
+  if (!avatarUrl) return
+
+  uploadingAvatar.value = true
+  try {
+    await userStore.updateProfile({ avatarUrl })
+    await userStore.fetchProfile()
+    uni.showToast({ title: '头像更新成功', icon: 'success' })
+  } catch (err: unknown) {
+    const msg = err instanceof Error ? err.message : '更新失败，请重试'
+    uni.showToast({ title: msg, icon: 'none' })
+  } finally {
+    uploadingAvatar.value = false
+  }
+}
+
 // ─── Phone binding ────────────────────────────────────────
 async function handleGetPhone(e: {
   detail: { encryptedData: string; iv: string; errMsg: string }
@@ -204,6 +225,17 @@ onMounted(async () => {
   border-bottom: 1rpx solid #f0ece8;
 }
 
+.avatar-btn {
+  background: transparent;
+  border: none;
+  padding: 0;
+  margin: 0;
+
+  &::after {
+    border: none;
+  }
+}
+
 .avatar-wrap {
   position: relative;
   width: 160rpx;