Ship signup sheet, subscribe reminders, cover crop, and theme updates.

Wire real WeChat app config, prefer activity cover over posters, and add admin cover cropping for the home banner.

Co-authored-by: Cursor <cursoragent@cursor.com>

miniprogram/pages/past-edit/past-edit.js

@@ -12,12 +12,29 @@ function chooseOne(mediaType) {
       success: (res) => {
         const file = res.tempFiles && res.tempFiles[0]
         if (file && file.tempFilePath) resolve(file.tempFilePath)
+        else reject(new Error('未选择文件'))
       },
       fail: reject
     })
   })
 }
 
+// Crop to a wide banner ratio before upload (closest built-in scale is 16:9).
+function cropCover(filePath) {
+  return new Promise((resolve, reject) => {
+    if (!wx.cropImage) {
+      resolve(filePath)
+      return
+    }
+    wx.cropImage({
+      src: filePath,
+      cropScale: '16:9',
+      success: (res) => resolve(res.tempFilePath || filePath),
+      fail: () => resolve(filePath)
+    })
+  })
+}
+
 function uploadWithLoading(filePath) {
   wx.showLoading({ title: '上传中', mask: true })
   return api.uploadMedia(filePath).then(
@@ -71,6 +88,7 @@ Page({
 
   pickCover() {
     chooseOne('image')
+      .then(cropCover)
       .then(uploadWithLoading)
       .then((data) => this.setData({ cover: data.url, coverPreview: media.absUrl(data.url) }))
       .catch((error) => {