no LoseLife (ADR-0005). SettleDeath / SettleCompletion defer to the
Attempt's terminal outcome, so both are atomic and idempotent.
SettleCompletion branches on HasCleared itself - a Replay cannot bank
or move campaign position backwards (ADR-0003).
Campaign value object holds authored level order; ReachableLevels is
derived, replacing the stored UnlockedLevels. Coins.IsAtLeast driven
out by cross-scope affordability.
29 tests. CONTEXT.md: Campaign, Settle.
