fix(ui): 调整UI元素的边框内边距并新增背景预制体

1.  调整ui6.plist中多个Sprite组件的border边框参数，修正显示排版
2.  新增boghbg背景预制体文件及其元数据配置

assets/resources/gui/auie/boghbg.prefab.meta

@@ -0,0 +1,13 @@
+{
+  "ver": "1.1.50",
+  "importer": "prefab",
+  "imported": true,
+  "uuid": "56a982e0-00ae-4ea4-a412-b54666d0e78b",
+  "files": [
+    ".json"
+  ],
+  "subMetas": {},
+  "userData": {
+    "syncNodeName": "boghbg"
+  }
+}

assets/resources/gui/ui6.plist.meta

@@ -3704,10 +3704,10 @@
         "height": 53,
         "rawWidth": 96,
         "rawHeight": 53,
-        "borderTop": 0,
-        "borderBottom": 0,
-        "borderLeft": 0,
-        "borderRight": 0,
+        "borderTop": 26.5,
+        "borderBottom": 26.5,
+        "borderLeft": 48,
+        "borderRight": 48,
         "packable": true,
         "pixelsToUnit": 100,
         "pivotX": 0.5,
@@ -3750,10 +3750,10 @@
         "height": 53,
         "rawWidth": 96,
         "rawHeight": 53,
-        "borderTop": 0,
-        "borderBottom": 0,
-        "borderLeft": 0,
-        "borderRight": 0,
+        "borderTop": 26.5,
+        "borderBottom": 26.5,
+        "borderLeft": 48,
+        "borderRight": 48,
         "packable": true,
         "pixelsToUnit": 100,
         "pivotX": 0.5,
@@ -3798,8 +3798,8 @@
         "rawHeight": 44,
         "borderTop": 0,
         "borderBottom": 0,
-        "borderLeft": 0,
-        "borderRight": 0,
+        "borderLeft": 9,
+        "borderRight": 9,
         "packable": true,
         "pixelsToUnit": 100,
         "pivotX": 0.5,
@@ -3934,10 +3934,10 @@
         "height": 45,
         "rawWidth": 88,
         "rawHeight": 45,
-        "borderTop": 0,
-        "borderBottom": 0,
-        "borderLeft": 0,
-        "borderRight": 0,
+        "borderTop": 22.5,
+        "borderBottom": 22.5,
+        "borderLeft": 44,
+        "borderRight": 44,
         "packable": true,
         "pixelsToUnit": 100,
         "pivotX": 0.5,