fix(detail): implement proper recharge navigation

replace placeholder toast with actual recharge page navigation, and add a failure callback to show error toast on navigation fail

src/pages-aigc/detail/detail.vue

@@ -229,7 +229,10 @@ const handleBack = () => {
 };
 
 const handleRecharge = () => {
-  showPlaceholderToast("积分充值");
+  uni.navigateTo({
+    url: "/pages-aigc/recharge/recharge",
+    fail: () => showPlaceholderToast("打开充值页面失败"),
+  });
 };
 
 const downloadMedia = (url) =>