docs: 添加管理平台标准加密算法 Kotlin 参考实现

docs/工具箱端-授权对接指南/utils/RegionUtil.kt

@@ -0,0 +1,22 @@
+package top.tangyh.lamp.filing.utils
+
+import kotlin.text.substring
+
+object RegionUtil {
+    fun getLevel(code: String?): String {
+        if (code == null || code.length != 6) {
+            return "无效编码"
+        }
+
+        val province = code.substring(0, 2)
+        val city = code.substring(2, 4)
+        val county = code.substring(4, 6)
+
+        return when {
+            city == "00" && county == "00" -> "province"
+            city != "00" && county == "00" -> "city"
+            county != "00" -> "county"
+            else -> "未知级别"
+        }
+    }
+}