Add product price history model and database schema: Implement associations for ProductPriceHistory with ProductType and RegionData. Update FalukantService to utilize active character for user-related operations. Ensure product price history table exists in the database with appropriate structure and indexing.

backend/models/index.js

@@ -89,6 +89,7 @@ import Learning from './falukant/data/learning.js';
 import Credit from './falukant/data/credit.js';
 import DebtorsPrism from './falukant/data/debtors_prism.js';
 import HealthActivity from './falukant/log/health_activity.js';
+import ProductPriceHistory from './falukant/log/product_price_history.js';
 
 // — Match3 Minigame —
 import Match3Campaign from './match3/campaign.js';
@@ -239,6 +240,7 @@ const models = {
   Credit,
   DebtorsPrism,
   HealthActivity,
+  ProductPriceHistory,
   RegionDistance,
   VehicleType,
   Vehicle,