fix(chat): 채팅방 메시지 전송 API

- 빈 메시지이면 전송하지 않고 반환

src/main/kotlin/kr/co/vividnext/sodalive/chat/room/controller/ChatRoomController.kt

@@ -133,6 +133,10 @@ class ChatRoomController(
         if (member == null) throw SodaException("로그인 정보를 확인해주세요.")
         if (member.auth == null) throw SodaException("본인인증을 하셔야 합니다.")
 
-        ApiResponse.ok(chatRoomService.sendMessage(member, chatRoomId, request.message))
+        if (request.message.isBlank()) {
+            ApiResponse.error()
+        } else {
+            ApiResponse.ok(chatRoomService.sendMessage(member, chatRoomId, request.message))
+        }
     }
 }