feat(saml): update host retrieval in SAML2 login success handler to use X-Forwarded-Host header

Author: mjabascal10

backend/src/main/java/com/park/utmstack/security/saml/Saml2LoginSuccessHandler.java

@@ -42,7 +42,7 @@ public void onAuthenticationSuccess(HttpServletRequest request,
                                         Authentication authentication) throws IOException {
 
         String scheme = Objects.requireNonNullElse(request.getHeader("X-Forwarded-Proto"), request.getScheme());
-        String host = Objects.requireNonNullElse(request.getHeader("Host"), request.getServerName());
+        String host = Objects.requireNonNullElse(request.getHeader("X-Forwarded-Host"), request.getServerName());
         String frontBaseUrl = scheme + "://" + host;
 
         Saml2AuthenticatedPrincipal samlUser = (Saml2AuthenticatedPrincipal) authentication.getPrincipal();