Fix certbot cronjob: remove TTY flags and ensure nginx reloads only on certbot success

[Copilot]

The documented certbot renewal cronjob had two bugs: -it flags on docker exec cause failures in cron (no TTY), and docker compose up exits zero even when certbot fails, causing nginx to reload with stale or no new certs.

Changes

• Remove -it from docker exec in cronjob — cron has no TTY; flags are only appropriate for interactive use (kept in the manual step 6)
• Add --abort-on-container-exit --exit-code-from certbot — propagates certbot's exit code so the && chain gates nginx reload on actual certbot success

# Before
0 0 * * 0 cd /home/ubuntu/cht/certbot && docker compose up && docker exec -it cht_nginx_1 nginx -s reload

# After
0 0 * * 0 cd /home/ubuntu/cht/certbot && docker compose up --abort-on-container-exit --exit-code-from certbot && docker exec cht_nginx_1 nginx -s reload

---

💬 Send tasks to Copilot coding agent from Slack and Teams to turn conversations into code. Copilot posts an update in your thread when it's finished.