Add production Docker Compose file for external PostgreSQL integration

- Introduced `docker-compose.prod.yml` for production deployment.
- Configured service to connect to an external PostgreSQL instance.
- Set environment variables for JWT and database connection strings.
- Defined network and volume for data protection keys.

Dockerfile

@@ -35,8 +35,13 @@ WORKDIR /app
 RUN apt-get update && apt-get install -y --no-install-recommends \
     libssl3 \
     ca-certificates \
+    nfs-common \
+    default-mysql-client \
     && rm -rf /var/lib/apt/lists/*
 
+# Docker CLI — used for local swarm operations when running on the same manager node
+COPY --from=docker:27-cli /usr/local/bin/docker /usr/local/bin/docker
+
 COPY --from=dotnet-build /app/publish .
 
 # Data Protection keys must survive restarts — mount a volume here