feat: upgrade to multi-model ensemble system

- Updated DB schemas: added 'strategy' to trades, new 'hourly_model_predictions' wide table
- Refactored backend: api/models.py, api/prediction_service.py to support wide format
- Updated trader: auto_trade_polymarket.py now logs strategy and saves to new table
- Updated frontend: index.html and app.js to display multi-model accuracy and trade strategy

api/main.py

@@ -106,8 +106,8 @@ async def get_monthly_accuracy(
         service = get_prediction_service()
         service.ensure_predictions_for_month(month)
         
-        # 获取统计
-        stats = PredictionModel.get_monthly_stats(month)
+        # 获取统计 (使用 V2 方法)
+        stats = PredictionModel.get_monthly_stats_v2(month)
         
         return {
             "success": True,
@@ -135,8 +135,8 @@ async def get_daily_accuracy(
         service = get_prediction_service()
         service.ensure_predictions_for_month(month)
         
-        # 获取统计
-        result = PredictionModel.get_daily_stats(month=month, page=page, limit=limit)
+        # 获取统计 (使用 V2 方法)
+        result = PredictionModel.get_daily_stats_v2(month=month, page=page, limit=limit)
         
         return {
             "success": True,
@@ -155,8 +155,8 @@ async def get_hourly_accuracy(date: str):
         service = get_prediction_service()
         service.ensure_predictions_for_date(date)
         
-        # 获取详情
-        details = PredictionModel.get_hourly_details(date)
+        # 获取详情 (使用 V2 方法)
+        details = PredictionModel.get_hourly_details_v2(date)
         
         return {
             "success": True,