Unify error handling and HTTP statuses

Signed-off-by: Sean Du <do4suki@gmail.com>

internal/handler/live/reward.go

@@ -9,6 +9,7 @@ import (
 	"honoka-chan/internal/session"
 	honokautils "honoka-chan/internal/utils"
 	"honoka-chan/pkg/utils"
+	"net/http"
 	"time"
 
 	"github.com/gin-gonic/gin"
@@ -172,7 +173,7 @@ func BuildRewardResp(ss *session.Session, playRewardReq liveschema.RewardReq, is
 			PresentCnt:                   0,
 		},
 		ReleaseInfo: []any{},
-		StatusCode:  200,
+		StatusCode:  http.StatusOK,
 	}
 
 	if playRewardReq.MaxCombo >= liveInfo.SRankCombo {