Fix errcheck violations across 11 repo files by wrapping deferred
rows.Close() and tx.Rollback() calls to discard the error return.
Fix unchecked Scan/Exec calls in guild store tests. Fix staticcheck
SA9003 empty branch in test helpers.
Add 6 mock-based unit tests for GetCharacterSaveData covering nil
savedata, sql.ErrNoRows, DB errors, compressed round-trip,
new-character skip, and config mode/pointer propagation.
Gacha stepup progress now resets when queried after the most recent
noon boundary, using a new created_at column on gacha_stepup.
Guild member rp_today rolls into rp_yesterday lazily when members are
enumerated after noon, using a new rp_reset_at column on guilds.
Both follow the established lazy-reset pattern from the cafe handler.
Centralizes all gacha_shop/gacha_entries/gacha_items/gacha_stepup/gacha_box
table access into GachaRepository (15 methods) and all user_binary house
columns, warehouse, and titles table access into HouseRepository (17 methods).
Eliminates all direct DB calls from handlers_gacha.go and handlers_house.go.
