Prepend a guard that runs `autoload -Uz compinit && compinit` when compdef
isn't defined, so the generated zsh completion works without oh-my-zsh or if
sourced before compinit.
Generate a click completion file for bash/zsh and source it from the alias
block. Click's generated script queries completions by invoking the command
— but `ci` is a sudo shell function (env vars don't survive sudo, and `env
VAR=x ci` can't call a function), so rewrite the query to call the venv
python directly (read-only, no sudo) and drop zsh's `$+commands[ci]` guard.
Writes ~/.ci-completion.<shell>; removed cleanly on --uninstall (block strip).
scripts/install-ci-alias.sh installs `ci` (runs the orchestrator as ci-runner
via the prod venv) and `ci-me` (current user). Idempotent, marker-bounded;
supports --system (/etc/profile.d), --uninstall. setup-host-linux.sh gains a
step [7/7] that installs it system-wide, passing CI_PROD_PYTHON/CI_RUN_USER.
Simone