Adds POST /campaign/regist_serial_code with 9 integration tests covering
success path, all disqualifier conditions (unknown/disabled/expired/future/
already-redeemed/unsupported-reward-type), 401 on missing auth, and case-
sensitivity. IsSupportedGiftRewardType uses gift-wire literals (1/4/9) not
UserGoodsType enum values, matching GiftController.WireRewardTypeToUserGoodsType.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
0d32d2167b