fix: 补充borderCornerRadius属性定义修复编译资源链接失败

在 winboll/src/main/res/values/attrs.xml 中添加缺失的
borderCornerRadius 属性声明，该属性被 bg_container_border.xml
引用但未在当前激活的模块中定义，导致 assembleBetaDebug 编译
时 AAPT 报错 resource attr/borderCornerRadius not found。

winboll/build.properties

@@ -1,8 +1,8 @@
 #Created by .winboll/winboll_app_build.gradle
-#Fri May 15 13:48:45 CST 2026
+#Fri May 15 14:13:24 CST 2026
 stageCount=2
 libraryProject=libwinboll
 baseVersion=15.20
 publishVersion=15.20.1
-buildCount=2
+buildCount=5
 baseBetaVersion=15.20.2

winboll/src/main/res/values/attrs.xml

@@ -1,5 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
+    <attr name="borderCornerRadius" format="dimension" />
+
     <declare-styleable name="CustomToolbar">
         <attr name="toolbarTitle" format="string" />
         <attr name="toolbarTitleColor" format="color" />