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.wxss

@@ -396,42 +396,123 @@
   color: rgba(255, 255, 255, 0.6);
 }
 
-/* ===== 分享提示 ===== */
-.share-tip {
+/* ===== 分享操作区 ===== */
+.action-section {
+  margin-top: 64rpx;
+  padding: 32rpx;
+  background: rgba(255, 255, 255, 0.03);
+  border-radius: 24rpx;
+  border: 2rpx solid rgba(255, 255, 255, 0.05);
+}
+
+.action-header {
+  margin-bottom: 24rpx;
+}
+
+.action-title {
+  font-size: 28rpx;
+  color: rgba(255, 255, 255, 0.6);
+}
+
+.action-buttons {
+  display: flex;
+  gap: 24rpx;
+}
+
+.action-btn {
+  flex: 1;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 12rpx;
+  padding: 28rpx 24rpx;
+  border-radius: 20rpx;
+  border: none;
+  background: transparent;
+  line-height: normal;
+}
+
+.action-btn::after {
+  border: none;
+}
+
+.btn-share {
+  background: rgba(7, 193, 96, 0.15);
+  border: 2rpx solid rgba(7, 193, 96, 0.3);
+}
+
+.btn-poster {
+  background: rgba(255, 215, 0, 0.15);
+  border: 2rpx solid rgba(255, 215, 0, 0.3);
+}
+
+.action-icon {
+  font-size: 36rpx;
+}
+
+.action-text {
+  font-size: 28rpx;
+  color: #ffffff;
+  font-weight: 500;
+}
+
+/* ===== 推广提示区 ===== */
+.promo-section {
+  margin-top: 32rpx;
+}
+
+.promo-card {
   display: flex;
   align-items: center;
   justify-content: space-between;
   padding: 32rpx;
-  background: linear-gradient(90deg, rgba(255, 215, 0, 0.1) 0%, transparent 100%);
+  background: linear-gradient(135deg, rgba(255, 215, 0, 0.1) 0%, rgba(255, 165, 0, 0.05) 100%);
   border: 2rpx solid rgba(255, 215, 0, 0.2);
   border-radius: 24rpx;
 }
 
-.tip-content {
+.promo-left {
+  display: flex;
+  align-items: center;
+  gap: 20rpx;
+}
+
+.promo-icon {
+  width: 80rpx;
+  height: 80rpx;
+  background: rgba(255, 215, 0, 0.2);
+  border-radius: 50%;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  font-size: 36rpx;
+}
+
+.promo-info {
   flex: 1;
 }
 
-.tip-title {
-  font-size: 28rpx;
+.promo-title {
+  font-size: 30rpx;
   color: #ffffff;
-  font-weight: 500;
+  font-weight: 600;
   display: block;
 }
 
-.tip-desc {
+.promo-desc {
   font-size: 24rpx;
-  color: rgba(255, 255, 255, 0.6);
+  color: rgba(255, 255, 255, 0.5);
   display: block;
   margin-top: 8rpx;
 }
 
-.tip-btn {
-  padding: 16rpx 32rpx;
-  background: #FFD700;
-  color: #000000;
-  font-size: 28rpx;
-  font-weight: 500;
-  border-radius: 16rpx;
+.promo-right {
+  padding-left: 20rpx;
+}
+
+.promo-arrow {
+  font-size: 32rpx;
+  color: #FFD700;
 }
 
 /* ===== 弹窗 ===== */
@@ -792,3 +873,56 @@
   font-size: 28rpx;
   color: rgba(255, 255, 255, 0.8);
 }
+
+/* ===== 海报弹窗 ===== */
+.poster-modal {
+  padding-bottom: calc(64rpx + env(safe-area-inset-bottom));
+}
+
+.poster-preview {
+  display: flex;
+  justify-content: center;
+  margin: 32rpx 0;
+  padding: 24rpx;
+  background: rgba(0, 0, 0, 0.3);
+  border-radius: 24rpx;
+}
+
+.poster-canvas {
+  border-radius: 16rpx;
+  box-shadow: 0 16rpx 48rpx rgba(0, 0, 0, 0.5);
+}
+
+.poster-actions {
+  display: flex;
+  gap: 24rpx;
+  margin-bottom: 24rpx;
+}
+
+.poster-btn {
+  flex: 1;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 12rpx;
+  padding: 28rpx;
+  border-radius: 24rpx;
+  font-size: 30rpx;
+  font-weight: 500;
+}
+
+.btn-save {
+  background: linear-gradient(135deg, #00CED1 0%, #20B2AA 100%);
+  color: #ffffff;
+}
+
+.btn-icon {
+  font-size: 32rpx;
+}
+
+.poster-tip {
+  font-size: 24rpx;
+  color: rgba(255, 255, 255, 0.4);
+  text-align: center;
+  display: block;
+}