refactor(modules): propagate UserError in quest, trade, and class services

src/modules/trade/trade.service.ts

@@ -1,5 +1,7 @@
 import type { TradeSession, TradeParticipant } from "./trade.types";
 import { DrizzleClient } from "@/lib/DrizzleClient";
+import { withTransaction } from "@/lib/db";
+import { UserError } from "@/lib/errors";
 import { economyService } from "@/modules/economy/economy.service";
 import { inventoryService } from "@/modules/inventory/inventory.service";
 import { itemTransactions } from "@/db/schema";