refactor(ui): update staff identity label to "官方"

Change staff identity display text from "职工认证" to "官方" and update
corresponding colors to gold theme in UserProfileHeader and
VerificationSettingsScreen.

src/screens/profile/VerificationSettingsScreen.tsx

@@ -57,7 +57,7 @@ const IDENTITY_TEXT: Record<string, string> = {
   general: '普通用户',
   student: '在校学生',
   teacher: '教职工',
-  staff: '工作人员',
+  staff: '官方工作人员',
   alumni: '校友',
   external: '外部人员',
 };