The captured shape ({"1":[], "3":[], "4":[]}) is the empty-period
wire echo; the client parser (LoadDetail.cs:553) only reads normal/total/
campaign. Table, entity, seed, and importer were never wired to a code path.
Replaced by config-section catalog + service in the follow-up commits.
/mypage/index data.colosseum_info and /arena_colosseum/{top,get_fee_info}
now both project through ColosseumLobbyInfoBuilder.Build(ColosseumSeasonConfig).
One source of truth for the home-tab gating and the lobby reads — admins
flip the season on by writing to GameConfigs (per the runbook), no second
table to keep in sync.
* New ColosseumLobbyInfoBuilder — static projection from ColosseumSeasonConfig
to the wire ColosseumLobbyInfo. Replaces ArenaColosseumController's private
BuildColosseumInfo and MyPageController's BuildColosseumInfo(ColosseumConfig).
* MyPageController reads ColosseumSeasonConfig via IGameConfigService; the
IGlobalsRepository.GetCurrentColosseum() call goes away.
* MyPageIndexResponse.ColosseumInfo retyped to the new ColosseumLobbyInfo.
* ColosseumSalesPeriodInfo relocated into the ArenaColosseum namespace
alongside the rest of the family DTOs.
* Drops: Colosseums DB table (migration DropColosseumsTable), ColosseumConfig
entity, the captured-shape Models.Dtos.ColosseumInfo DTO, ColosseumSeed,
MyPageGlobalsImporter.ImportColosseumAsync + seed file colosseum.json,
IGlobalsRepository.GetCurrentColosseum + impl, the two related tests.
Net: home-screen Grand Prix tab now hidden by default because the season
ships with IsColosseumPeriod=false. Full suite: 1345/1345 (was 1347 — the
2 dropped tests covered the now-dead surface).
