Restrict battle item stocks to allies

scripts/verify-battle-save-normalization.mjs

@@ -101,6 +101,7 @@ try {
     ['invalid item stock count', { itemStocks: { 'liu-bei': { bean: -1 } } }],
     ['too many item stock count', { itemStocks: { 'liu-bei': { bean: 4, wine: 2 } } }],
     ['unknown item stock unit id', { itemStocks: { 'ghost-unit': { bean: 1 } } }],
+    ['enemy item stock unit id', { itemStocks: { 'rebel-1': { bean: 1 } } }],
     ['unknown item stock item id', { itemStocks: { 'liu-bei': { phantomItem: 1 } } }],
     ['invalid buff turns', { battleBuffs: [{ ...validState.battleBuffs[0], turns: 0 }] }],
     ['too many buff turns', { battleBuffs: [{ ...validState.battleBuffs[0], turns: 10 }] }],

src/game/state/battleSaveState.ts

@@ -430,6 +430,7 @@ function isOptionalItemStockRecord(value: unknown, options: BattleSaveValidation
   return Object.entries(value).every(
     ([unitId, stocks]) =>
       isKnownUnitId(unitId, options) &&
+      (!options.validAllyUnitIds || options.validAllyUnitIds.has(unitId)) &&
       isRecord(stocks) &&
       Object.keys(stocks).length <= itemReferenceLimit(options) &&
       Object.entries(stocks).every(