Move all battle state from IPokemon to an ephemeral IBattlePokemon wrapper

Plugins/PkmnLib.Plugin.Gen7/Scripts/Pokemon/StockpileEffect.cs

@@ -3,13 +3,13 @@ namespace PkmnLib.Plugin.Gen7.Scripts.Pokemon;
 [Script(ScriptCategory.Pokemon, "stockpile_effect")]
 public class StockpileEffect : Script, IScriptStack
 {
-    private IPokemon? _pokemon;
+    private IBattlePokemon? _pokemon;
     public int StockpileCount { get; set; } = 1;
 
     /// <inheritdoc />
     public override void OnAddedToParent(IScriptSource source)
     {
-        if (source is not IPokemon pokemon)
+        if (source is not IBattlePokemon pokemon)
         {
             throw new InvalidOperationException("StockpileEffect can only be added to a Pokemon.");
         }