fix(api-gateway): correct Kong routing for trading-service

- Change strip_path to true to strip /api/v2/trading prefix
- Add /api/v2 to upstream URL so requests route correctly
- Revert accidental main.ts change

Request flow: /api/v2/trading/asset/market -> strip /api/v2/trading -> /asset/market -> upstream /api/v2/asset/market

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/api-gateway/kong.yml

@@ -309,18 +309,19 @@ services:
 
   # ---------------------------------------------------------------------------
   # Trading Service 2.0 - 交易服务
+  # 前端路径: /api/v2/trading/... -> 后端路径: /api/v2/...
   # ---------------------------------------------------------------------------
   - name: trading-service-v2
-    url: http://192.168.1.111:3022
+    url: http://192.168.1.111:3022/api/v2
     routes:
       - name: trading-v2-api
         paths:
           - /api/v2/trading
-        strip_path: false
+        strip_path: true
       - name: trading-v2-health
         paths:
           - /api/v2/trading/health
-        strip_path: false
+        strip_path: true
 
   # ---------------------------------------------------------------------------
   # Mining Admin Service 2.0 - 挖矿管理后台服务

backend/services/trading-service/src/main.ts

@@ -20,7 +20,7 @@ async function bootstrap() {
     credentials: true,
   });
 
-  app.setGlobalPrefix('api/v2/trading');
+  app.setGlobalPrefix('api/v2');
 
   const config = new DocumentBuilder()
     .setTitle('Trading Service API')