feat(items): add Poison Wing (12/240) and Poison Cape (12/241)

Basic wings via the simple CreateWing overload (base defense, class
restriction, CanFly; no options). Poison Wing=Dark Knight, Poison
Cape=Dark Lord+Rage Fighter. Update-plugin v98 + fresh-seed via
Wings.Initialize().

src/Persistence/Initialization/Updates/UpdateVersion.cs

@@ -494,4 +494,9 @@ public enum UpdateVersion
     /// The version of the <see cref="AddImportedMapsUpdateSeason6"/> (Acheron, Debenter, Uruk, Ferea).
     /// </summary>
     AddImportedMapsSeason6 = 97,
+
+    /// <summary>
+    /// The version of the <see cref="AddPoisonWingsUpdateSeason6"/> (Poison Wing 12/240, Poison Cape 12/241).
+    /// </summary>
+    AddPoisonWingsSeason6 = 98,
 }