- deploy.sh: add cert-<domain> command for zero-downtime SSL issuance
- new-app.sh: SSH as deploy user with key from Bitwarden instead of personal user
- remove DEPLOY_USER/DEPLOY_HOST env var requirements
- update all docs to reflect new flow
Dispatch now validates the command format and routes to a single
deploy.sh that handles any app. This fixes first-deploy failures
for new apps (dispatch no longer needs a static case list) and
simplifies new-app.sh (no deploy script or dispatch update needed).
Also adds input validation to new-app.sh, set -euo pipefail to
deploy scripts, and dnf module reset before nodejs install.