fix: comment out emitter.complete() to allow keep-alive sessions for standard SSE MCP client

dap-gateway/src/main/java/io/shinhanlife/dap/dapms/sync/CustomWebMvcSseServerTransportProvider.java

@@ -179,8 +179,8 @@ public class CustomWebMvcSseServerTransportProvider implements McpServerTranspor
             log.info("Message sent to session handler");
             
             if (emitter != null && !map.containsKey("id")) {
-                emitter.complete();
-                log.info("Completed emitter for notification");
+                // emitter.complete();
+                log.info("Completed emitter for notification (disabled for keep-alive)");
             }
             
             return ResponseEntity.ok().build();
@@ -220,7 +220,7 @@ public class CustomWebMvcSseServerTransportProvider implements McpServerTranspor
                         
                         // Custom 프로토콜: 1회 요청당 1응답 후 종료 (스트림을 닫아버림)
                         // 클라이언트가 한 번의 POST 후 응답을 받고 연결을 끊기 때문
-                        this.emitter.complete();
+                        // this.emitter.complete();
                     }
                 } catch (Exception e) {
                     log.error("Error sending message to SSE emitter", e);