Incorrect LAMBDA_DOCKER_NETWORK prevents Lambda-to-LocalStack connectivity

When LAMBDA_DOCKER_NETWORK is manually configured without the docker-compose project name prefix, Lambda containers are created on the wrong network and cannot reach the LocalStack instance, causing startup timeouts and invocation failures.

Remove the LAMBDA_DOCKER_NETWORK configuration parameter entirely from docker-compose.yml. LocalStack will automatically detect the correct network name, including the docker-compose project prefix (e.g., 'nexiam-backend_nexhub-net' instead of just 'nexhub-net'). Restart LocalStack after removing this parameter.