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/signup/signup.wxss

@@ -1,52 +1,3 @@
-.page {
-  padding: 28rpx 32rpx 48rpx;
-}
-
-.card {
-  padding: 12rpx 32rpx 28rpx;
-  background: #ffffff;
-  border-radius: 28rpx;
-}
-
-.label {
-  display: block;
-  margin-top: 28rpx;
-  color: #6b7280;
-  font-size: 26rpx;
-}
-
-.input {
-  height: 88rpx;
-  margin-top: 8rpx;
-  border-bottom: 1rpx solid #eef0f3;
-  font-size: 32rpx;
-}
-
-.placeholder {
-  color: #c4c9d1;
-}
-
-.save {
-  height: 96rpx;
-  margin-top: 36rpx;
-  border-radius: 20rpx;
-  background: #128a80;
-  color: #ffffff;
-  font-size: 32rpx;
-  font-weight: 600;
-  display: flex;
-  align-items: center;
-  justify-content: center;
-}
-
-.save.busy {
-  opacity: 0.7;
-}
-
-.hint {
-  display: block;
-  margin-top: 20rpx;
-  text-align: center;
-  color: #9ca3af;
-  font-size: 24rpx;
+page {
+  background: transparent;
 }