Added database connection, added test and start with Testcontainers.

docker-compose.yaml

@@ -0,0 +1,18 @@
+services:
+
+  db:
+    image: postgres:18.3
+    restart: always
+    shm_size: 128mb
+    environment:
+      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}
+      POSTGRES_USER: ${POSTGRES_USER}
+      POSTGRES_DB: ${POSTGRES_DB}
+    ports:
+      - 12900:5432
+
+  adminer:
+    image: adminer
+    restart: always
+    ports:
+      - 12901:8080