Separate docker env from main backend defaults

backend/.env.docker

@@ -0,0 +1,19 @@
+# Backend
+DOMAIN=localhost
+ENVIRONMENT=local
+PROJECT_NAME="Districtr v2 backend"
+BACKEND_CORS_ORIGINS="http://localhost,http://localhost:5173,http://localhost:3000,http://127.0.0.1:3000"
+SECRET_KEY="super-secret"
+
+# Postgres
+DATABASE_URL=postgresql+psycopg://postgres:postgres@db:5432/districtr
+POSTGRES_SCHEME=postgresql+psycopg
+POSTGRES_USER=postgres
+POSTGRES_PASSWORD=postgres
+POSTGRES_DB=districtr
+POSTGRES_SERVER=db  # Use the service name `db` from docker-compose
+POSTGRES_PORT=5432
+
+# Volumes
+VOLUME_PATH=/data
+