- Add spawn and SpawnOptions imports and implement Execute.executeCommandInheritStdio
that runs commands with inherited stdio, logs errors, and rejects on non-zero exit.
- Update NginxConfigurator to run `nginx -t -c /etc/nginx/nginx.conf` via the new
inherit-stdio helper before reloading nginx.
Add ensure_placeholder_certificate to envsubst-on-templates.sh to generate a temporary self-signed cert when PRIMARY_DOMAIN is set but cert files are missing. Only export SSL listen/certificate directives if certs (real or placeholder) are available; otherwise disable HTTPS directives and emit warnings. Simplify PRIMARY_DOMAIN logging.
Also run "nginx -t" immediately after running the envsubst script in NginxConfigurator to validate generated config before attempting reload.
- WriteServerCertToDisk: read existing cert/key from disk and compare with DB values; skip writing when unchanged. After writing, run envsubst-on-templates.sh and reload nginx with try/catch and logging.
- envsubst-on-templates.sh: derive PRIMARY_DOMAIN from HOST when not set, compute cert/key paths, and only export PROVISION_SSL_* directives when certificate files exist (otherwise clear directives and log).
