refs #712: authenticate backoffice MCP user tokens

src/main/java/com/cloudhandson/vpdbackoffice/service/McpUnauthorizedException.java

@@ -0,0 +1,9 @@
+package com.cloudhandson.vpdbackoffice.service;
+
+/** Deliberately generic MCP authentication failure; never include token material. */
+public class McpUnauthorizedException extends RuntimeException {
+
+  public McpUnauthorizedException() {
+    super("유효한 HMM 사용자 Bearer Token이 필요합니다.");
+  }
+}