feat: 海报优化+小程序码生成API

1. 阅读页&推广中心海报去掉邀请码
2. 新增小程序码生成API（带推荐人ID参数）
3. 海报使用真实小程序码（扫码绑定推荐关系）
4. 修复章节数据库同步

miniprogram/pages/referral/referral.js

@@ -144,7 +144,23 @@ Page({
     
     try {
       const ctx = wx.createCanvasContext('promoPosterCanvas', this)
-      const { referralCode, userInfo, earnings, referralCount, distributorShare } = this.data
+      const { userInfo, earnings, referralCount, distributorShare } = this.data
+      const userId = userInfo?.id || ''
+      
+      // 获取小程序码（带推荐人参数）
+      let qrcodeImage = null
+      try {
+        const scene = userId ? `ref=${userId.slice(0,20)}` : 'ref=soul'
+        const qrRes = await app.request('/api/miniprogram/qrcode', {
+          method: 'POST',
+          data: { scene, page: 'pages/index/index', width: 280 }
+        })
+        if (qrRes.success && qrRes.image) {
+          qrcodeImage = qrRes.image
+        }
+      } catch (e) {
+        console.log('[Poster] 获取小程序码失败，使用占位符')
+      }
       
       // 海报尺寸 300x450
       const width = 300
@@ -206,23 +222,43 @@ Page({
       ctx.setFillStyle('rgba(0,206,209,0.1)')
       ctx.fillRect(0, height - 80, width, 80)
       
-      // 小程序码占位
-      ctx.setFillStyle('#ffffff')
-      ctx.beginPath()
-      ctx.arc(width - 55, height - 40, 30, 0, Math.PI * 2)
-      ctx.fill()
-      ctx.setFillStyle('#00CED1')
-      ctx.setFontSize(9)
-      ctx.fillText('扫码', width - 62, height - 42)
-      ctx.fillText('购买', width - 62, height - 30)
-      
       // 底部提示
       ctx.setFillStyle('#ffffff')
       ctx.setFontSize(13)
-      ctx.fillText('长按识别 立即购买', 20, height - 45)
+      ctx.fillText('长按识别 立即购买', 20, height - 50)
       ctx.setFillStyle('rgba(255,255,255,0.6)')
       ctx.setFontSize(11)
-      ctx.fillText(`推广返利 ${distributorShare}%`, 20, height - 22)
+      ctx.fillText(`推广返利 ${distributorShare}%`, 20, height - 28)
+      
+      // 绘制小程序码
+      const drawQRCode = () => {
+        return new Promise((resolve) => {
+          if (qrcodeImage) {
+            const fs = wx.getFileSystemManager()
+            const filePath = `${wx.env.USER_DATA_PATH}/qrcode_promo_${Date.now()}.png`
+            const base64Data = qrcodeImage.replace(/^data:image\/\w+;base64,/, '')
+            
+            fs.writeFile({
+              filePath,
+              data: base64Data,
+              encoding: 'base64',
+              success: () => {
+                ctx.drawImage(filePath, width - 75, height - 70, 60, 60)
+                resolve()
+              },
+              fail: () => {
+                this.drawQRPlaceholder(ctx, width, height)
+                resolve()
+              }
+            })
+          } else {
+            this.drawQRPlaceholder(ctx, width, height)
+            resolve()
+          }
+        })
+      }
+      
+      await drawQRCode()
       
       ctx.draw(true, () => {
         wx.hideLoading()
@@ -236,6 +272,18 @@ Page({
     }
   },
   
+  // 绘制小程序码占位符
+  drawQRPlaceholder(ctx, width, height) {
+    ctx.setFillStyle('#ffffff')
+    ctx.beginPath()
+    ctx.arc(width - 45, height - 40, 30, 0, Math.PI * 2)
+    ctx.fill()
+    ctx.setFillStyle('#00CED1')
+    ctx.setFontSize(9)
+    ctx.fillText('扫码', width - 52, height - 42)
+    ctx.fillText('购买', width - 52, height - 30)
+  },
+  
   // 关闭海报弹窗
   closePosterModal() {
     this.setData({ showPosterModal: false })