feat: 海报生成功能+推广优化

1. 阅读页：
   - 添加"生成海报"和"分享给好友"按钮
   - 海报包含章节摘要+邀请码+小程序码占位
   - 优化推广提示区域，添加推广中心入口

2. 分销中心：
   - 完善海报生成功能（推广海报）
   - 去掉"更多分享方式"，改为"复制朋友圈文案"
   - 添加"分享给好友"小程序卡片按钮

3. 分享链接自动带分销ID

miniprogram/pages/read/read.wxml

@@ -80,13 +80,37 @@
           </view>
         </view>
 
-        <!-- 推广提示 -->
-        <view class="share-tip" bindtap="showShare">
-          <view class="tip-content">
-            <text class="tip-title">推荐好友，共同成长</text>
-            <text class="tip-desc">邀请好友加入，享90%推广收益</text>
+        <!-- 分享操作区 -->
+        <view class="action-section">
+          <view class="action-header">
+            <text class="action-title">分享这篇内容</text>
+          </view>
+          <view class="action-buttons">
+            <button class="action-btn btn-share" open-type="share">
+              <text class="action-icon">💬</text>
+              <text class="action-text">分享给好友</text>
+            </button>
+            <view class="action-btn btn-poster" bindtap="generatePoster">
+              <text class="action-icon">🖼️</text>
+              <text class="action-text">生成海报</text>
+            </view>
+          </view>
+        </view>
+
+        <!-- 推广提示 -->
+        <view class="promo-section">
+          <view class="promo-card" bindtap="goToReferral">
+            <view class="promo-left">
+              <view class="promo-icon">💰</view>
+              <view class="promo-info">
+                <text class="promo-title">推荐好友，共同成长</text>
+                <text class="promo-desc">邀请好友购买，享90%推广收益</text>
+              </view>
+            </view>
+            <view class="promo-right">
+              <text class="promo-arrow">→</text>
+            </view>
           </view>
-          <view class="tip-btn">立即推广</view>
         </view>
       </view>
     </view>
@@ -171,34 +195,27 @@
     </view>
   </view>
 
-  <!-- 分享弹窗 -->
-  <view class="modal-overlay" wx:if="{{showShareModal}}" bindtap="closeShareModal">
-    <view class="modal-content share-modal" catchtap="stopPropagation">
+  <!-- 海报生成弹窗 -->
+  <view class="modal-overlay" wx:if="{{showPosterModal}}" bindtap="closePosterModal">
+    <view class="modal-content poster-modal" catchtap="stopPropagation">
       <view class="modal-header">
-        <text class="modal-title">分享文章</text>
-        <view class="modal-close" bindtap="closeShareModal">✕</view>
+        <text class="modal-title">生成海报</text>
+        <view class="modal-close" bindtap="closePosterModal">✕</view>
       </view>
 
-      <view class="share-link-box">
-        <text class="link-label">你的专属分享链接</text>
-        <text class="link-url">https://soul.quwanzhi.com/read/{{sectionId}}</text>
-        <text class="link-tip">邀请码: 好友购买你获得90%佣金</text>
+      <!-- 海报预览 -->
+      <view class="poster-preview">
+        <canvas canvas-id="posterCanvas" class="poster-canvas" style="width: 300px; height: 450px;"></canvas>
       </view>
 
-      <view class="share-buttons">
-        <view class="share-btn" bindtap="copyLink">
-          <view class="share-btn-icon icon-copy">📋</view>
-          <text class="share-btn-text">复制链接</text>
-        </view>
-        <button class="share-btn" open-type="share">
-          <view class="share-btn-icon icon-wechat">微</view>
-          <text class="share-btn-text">微信好友</text>
-        </button>
-        <view class="share-btn" bindtap="goToReferral">
-          <view class="share-btn-icon icon-poster">🖼️</view>
-          <text class="share-btn-text">生成海报</text>
+      <view class="poster-actions">
+        <view class="poster-btn btn-save" bindtap="savePoster">
+          <text class="btn-icon">💾</text>
+          <text>保存到相册</text>
         </view>
       </view>
+
+      <text class="poster-tip">长按海报可直接分享到微信</text>
     </view>
   </view>