refactor(security): Change X-Tool-Server-API-Key header to apiKey

dap-gateway/src/main/java/io/shinhanlife/dap/mcg/service/ExecuteService.java

@@ -261,6 +261,10 @@ public class ExecuteService {
                     Map<String, String> headers = new java.util.HashMap<>();
                     headers.put("trace-id", context.requestId());
                     headers.put("request-id", java.util.UUID.randomUUID().toString());
+                    String apiKey = properties.toolServerApiKey();
+                    if (apiKey != null && !apiKey.isEmpty()) {
+                        headers.put("apiKey", apiKey);
+                    }
                     
                     ObjectNode pageArguments = paginationValidator.normalize(metadata, arguments);
                     LargeToolResponseService.Collector collector = largeResponses.newCollector(metadata.getName(), context.requestId());