feat(activity): 活动详情页分享改为生成海报（复用ContentSharePoster组件）

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

cfc-frontend/pages/activity/activity-detail/activity-detail.vue

@@ -79,7 +79,7 @@
           <text class="bottom-vendor" v-if="activity.vendorName">{{ activity.vendorName }}</text>
         </view>
         <view class="action-btns">
-          <button class="share-btn" open-type="share" @click="onShareTap">
+          <button class="share-btn" @click="generatePoster">
             <text class="share-btn-icon">📤</text>
           </button>
           <!-- 报名按钮（仅 requireRegistration=1 时显示） -->
@@ -241,17 +241,32 @@
     <view v-else class="empty-wrap">
       <text class="empty-text">活动不存在或已下架</text>
     </view>
+
+    <!-- 分享海报 -->
+    <ContentSharePoster
+      :show="showPoster"
+      :title="activity && activity.title"
+      :coverImage="activity && activity.coverImage"
+      :qrCodeBase64="posterQrCode"
+      typeLabel="活动推荐"
+      :dimensionCode="activity && activity.dimensionCode"
+      :summary="posterSummary"
+      :priceText="posterPriceText"
+      :inviteText="posterInviteText"
+      @close="closePoster"
+    />
   </view>
 </template>
 
 <script>
-import { getActivityDetail, activityCheckin, registerActivity, cancelActivityRegistration, getMyActivityRegistrations, submitActivityFeedback, getActivityFeedbackList, getMyActivityFeedback, getFamilyMembers } from '@/utils/api.js'
+import { getActivityDetail, activityCheckin, registerActivity, cancelActivityRegistration, getMyActivityRegistrations, submitActivityFeedback, getActivityFeedbackList, getMyActivityFeedback, getFamilyMembers, getShareQrCode } from '@/utils/api.js'
 import shareMixin from '../../../components/share-mixin.js'
 import MpHtml from '@/components/mp-html/mp-html.vue'
+import ContentSharePoster from '@/components/ContentSharePoster.vue'
 
 export default {
   mixins: [shareMixin],
-  components: { MpHtml },
+  components: { MpHtml, ContentSharePoster },
   data() {
     return {
       activityId: null,
@@ -278,7 +293,13 @@ export default {
       showRegModal: false,
       familyMembers: [],
       registrants: [],
-      regSubmitting: false
+      regSubmitting: false,
+      // 分享海报
+      showPoster: false,
+      posterQrCode: '',
+      posterSummary: '',
+      posterPriceText: '',
+      posterInviteText: ''
     }
   },
   onLoad: function(options) {
@@ -575,6 +596,33 @@ export default {
       this.registrants = []
       this.familyMembers = []
     },
+    // ===== 分享海报 =====
+    async generatePoster() {
+      if (!this.activity || !this.activity.id) return
+      uni.showLoading({ title: '生成海报中...' })
+      try {
+        var res = await getShareQrCode('pages/activity/activity-detail/activity-detail', 'id=' + this.activity.id)
+        if (res && res.data) {
+          this.posterQrCode = res.data.qrCodeBase64 || ''
+          this.posterSummary = this.buildPosterSummary()
+          this.posterPriceText = this.activity.price > 0 ? '¥' + this.activity.price : '免费'
+          this.posterInviteText = '「' + (uni.getStorageSync('nickname') || '好友') + '」邀请你一起参加这个活动'
+          this.showPoster = true
+        }
+      } catch (e) {
+        uni.showToast({ title: '生成失败', icon: 'none' })
+      } finally {
+        uni.hideLoading()
+      }
+    },
+    buildPosterSummary: function() {
+      var desc = (this.activity && this.activity.description) || ''
+      desc = desc.replace(/<[^>]+>/g, ' ').replace(/&nbsp;/g, ' ').replace(/\s+/g, ' ').trim()
+      return desc.length > 60 ? desc.substring(0, 60) + '...' : desc
+    },
+    closePoster: function() {
+      this.showPoster = false
+    },
     submitRegistration: function() {
       var self = this
       // Validate