Add migration for slayer points

src/module/migrations/004.ts

@@ -60,7 +60,14 @@ function getActorUpdateData(actorData: DeepPartial<Actor.Data>) {
             return itemData;
         }
     });
-    return hasItemUpdates ? { items } : undefined;
+    const updateData: Record<string, unknown> = {};
+    if (actorData.type === "character") {
+        updateData["data.slayerPoints"] = { value: 0 };
+    }
+    if (hasItemUpdates) {
+        updateData["items"] = items;
+    }
+    return updateData;
 }
 
 async function migrateScenes() {