🐛 fix(billing): I18n and styles

apps/admin/locales/en-US/common.json

@@ -1,4 +1,8 @@
 {
+  "billing": {
+    "title": "赞助商",
+    "description": "赞助有助于 PPanel 继续发布更新!"
+  },
   "empty": [
     "Imagine this place filled with exciting content! For now, you'll have to use your imagination...",
     "This area mysteriously disappeared, but we're summoning it back!",

apps/admin/locales/zh-CN/common.json

@@ -1,4 +1,8 @@
 {
+  "billing": {
+    "title": "赞助商",
+    "description": "赞助有助于 PPanel 继续发布更新!"
+  },
   "empty": [
     "想象一下这里充满了精彩的内容！暂时只能靠想象了…",
     "这片区域神秘消失了，我们正在召唤它回来！",