fix: image URLs incorrectly using API base URL instead of image base URL

Images are served from MinIO directly, not through /prod-api proxy.
Add imageBaseUrl to config and use it in fixImageUrl() and WXML templates.
This fixes images not loading on order list and detail pages.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

coupon/pages/order/order.js

@@ -7,7 +7,7 @@ Page({
     nav_type: 1,
     all: true,
     height: '',
-    url: app.globalData.url,
+    url: app.globalData.imageBaseUrl,
     statusType: ["全部", "待接单", "已接单", "服务中", "待支付", "已完成","已取消"],
     status: ["", "0", "1", "2", "3","4","-2"],
     currentType: 0,

coupon/pages/orderdetail/orderdetail.js

@@ -14,7 +14,7 @@ Page({
     qrcode: '',
     id: '',
     item: {},
-    url: app.globalData.url,
+    url: app.globalData.imageBaseUrl,
     refund: '',
     charge_phone: '',
     refund_box: false,