feat(progression): capabilities the adapters need (commit A of the swap)

no behaviour change - additive only.

GrantSkill: pickups are free unlocks, and collecting one already owned is
a no-op rather than a free upgrade.
RevokeSkill: for skills that consume themselves (brick shield).
AbandonAttempt: leaving a level without dying, so no life is charged.

ApplyCheat rewrites the Playthrough through its snapshot rather than via
SetLives/AddCoins mutators, which ADR-0005 rules out - a bare mutator is
an invitation, and the old code had two paths to exactly that. Every
value is re-validated on the way back in and a rejected cheat leaves the
Playthrough untouched, which is asserted.

73 tests.

progression/Playthrough.cs

@@ -130,6 +130,12 @@ public sealed class Playthrough
     /// Takes the events raised since the last drain, clearing them. The composition root drains
     /// once after each use case and republishes.
     /// </summary>
+    /// <summary>
+    /// Forgets an owned Skill. Exists for Skills that consume themselves — the brick shield is spent
+    /// when it breaks — so this is gameplay, not a cheat.
+    /// </summary>
+    public bool RevokeSkill(SkillId skill) => _ownedSkills.Remove(skill);
+
     public IReadOnlyList<ProgressionEvent> DrainEvents() => _events.Drain();
 
     public PlaythroughSnapshot Export() => new(