chore: update CI workflow to use explicit db host and port mapping

.github/workflows/ci.yml

@@ -11,6 +11,8 @@ env:
   DB_NAME: piku_test_db
   DB_USER: test
   DB_PASSWORD: password123
+  DB_HOST: 127.0.0.1
+  DB_PORT: 5442
 
 jobs:
   setup-environment:
@@ -74,11 +76,8 @@ jobs:
           POSTGRES_USER: ${{ env.DB_USER }}
           POSTGRES_PASSWORD: ${{ env.DB_PASSWORD }}
         ports:
-          - 5432
+          - 5442:5432
         options: --health-cmd pg_isready --health-interval 10s --health-timeout 5s --health-retries 5
-    env:
-      DB_HOST: 127.0.0.1
-      DB_PORT: ${{ job.services.postgres.ports['5432'] }}
     defaults:
       run:
         working-directory: ./backend