chore: upgrade PostgreSQL to v18 and restructure compose.yaml

compose.yaml

@@ -1,24 +1,22 @@
 services:
   app:
     build: .
-    ports:
-      - '3000:3000'
-    environment:
-      DATABASE_URL: postgres://postgres:postgres@db:5432/postgres
     depends_on:
       db:
         condition: service_healthy
+    ports:
+      - '3000:3000'
+    environment:
+      - DATABASE_URL=postgres://postgres:postgres@db:5432/postgres
 
   db:
-    image: postgres:17-alpine
+    image: postgres:18
-    # ports:
+    volumes:
-    #   - '5432:5432'
+      - pgdata:/var/lib/postgresql/data
     environment:
       POSTGRES_USER: postgres
       POSTGRES_PASSWORD: postgres
       POSTGRES_DB: postgres
-    volumes:
-      - pgdata:/var/lib/postgresql/data
     healthcheck:
       test: [ 'CMD', 'pg_isready', '-U', 'postgres' ]
       interval: 5s