feat: add stickers delete api

internal/handler/sadhna.go

@@ -141,6 +141,19 @@ func (h *SadhnaHandler) GiftableRewards(w http.ResponseWriter, r *http.Request)
 	response.JSON(w, http.StatusOK, list)
 }
 
+// DeleteCustomGift — DELETE /admin/reward-gifts/{key}
+func (h *SadhnaHandler) DeleteCustomGift(w http.ResponseWriter, r *http.Request) {
+	if err := h.svc.DeleteCustomGift(r.Context(), chi.URLParam(r, "key")); err != nil {
+		if errors.Is(err, repository.ErrRewardNotFound) {
+			response.Error(w, http.StatusNotFound, "no such custom gift")
+			return
+		}
+		response.Error(w, http.StatusBadRequest, err.Error())
+		return
+	}
+	response.NoContent(w)
+}
+
 type customGiftReq struct {
 	Name     string `json:"name"`
 	Meaning  string `json:"meaning"`