refs #712: authenticate backoffice MCP user tokens

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

@@ -0,0 +1,8 @@
+package com.cloudhandson.vpdbackoffice.service;
+
+/** Validates an HMM backoffice bearer token without retaining its plaintext value. */
+@FunctionalInterface
+public interface HmmMcpBearerAuthenticator {
+
+  HmmMcpPrincipal authenticate(String bearerToken);
+}