[refactor] SSE 세션 유지 30분으로 수정 (#157)

Author: silver-eunjoo

backend/src/main/java/io/f1/backend/domain/game/sse/app/SseService.java

@@ -17,7 +17,7 @@ public class SseService {
     private final SseEmitterRepository emitterRepository;
 
     public SseEmitter subscribe() {
-        SseEmitter emitter = new SseEmitter(30_000L);
+        SseEmitter emitter = new SseEmitter(1_800_000L);
         emitterRepository.save(emitter);
 
         try {