flat snapshot record per aggregate - separate files mean saving a run
doesn't rewrite the Profile, deleting a slot is deleting a file, and a
corrupt slot doesn't cost achievements or best times.
snapshots hold primitives so Restore re-runs the value-object factories;
a serialiser building LevelId directly would bypass every guard.
LoadResult has three outcomes: Absent != Corrupt. Collapsing them is the
bug where a version bump made ContinueGame overwrite the save.
Profile.Restore writes collections directly - replaying UnlockAchievement
would re-fire popups and Steam pushes on every load. 44 tests.
best times only improve; achievement unlock announces on the transition
only, so popup/Steam subscribers cannot double-fire; statistics are
increase-only (IncrementStat took any int).
RelockAchievement is console-only and documented as not reaching Steam -
a Steam achievement cannot be un-earned, so the disagreement is
permanent and deliberate.
refactor: extract EventLog, composed by both aggregates now that the
duplication actually exists. 34 tests.
