Trading: shop kind and trade.open schema; trade test passes the RPG Plus prologue

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

locale/schema_zh.properties

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+trading/schema/builtin/trade_open = 打开商店
+trading/schema/builtin/trade_open_desc = 与该商人的交易窗口
+trading/schema/field/shop = 商店
+trading/schema/kind/shop = 商店
+trading/schema/kind/shop_desc = 商人卖什么、收什么
+trading/schema/field/name = 名称
+trading/schema/field/currency = 货币
+trading/schema/field/sells = 出售
+trading/schema/field/item = 物品
+trading/schema/field/price = 价格
+trading/schema/field/buys = 收购