POST /host/delete-template: same two-step confirm gate, CSRF check, and
known-template containment as /host/backup, offloaded to a thread the same
way (rmtree on a multi-GB template dir is not instant). No backup-required
safety rail -- same confirm-gate as every other destructive action, nothing
more; the confirm summary spells out that clones can no longer be made from
the template until one is restored.
Also cleaned up the per-backup Delete button it sits next to: name+meta
grouped into one shrinkable unit so the row wraps as a block instead of the
delete button drifting away from a name that wrapped, and each backup is
now its own bordered line instead of a run-on flex list.
backup_template used a hardcoded _BACKUP_BASE_DIR=/var/lib/ci/backups; now derives <config.paths.root>/backups (matches the CLI --backup-base-dir default) per the plan's no-hardcoded-path gotcha. Tests no longer need to monkeypatch the constant.
Extracts pure, click-free cargo-cache status/purge and host disk/runner/
backup-template logic into operations/, mirroring the W1 pattern. Routes
commands/retention.py::_purge_cargo_cache through operations.cache while
preserving identical CLI output. commands/monitor.py is left untouched
(its refactor is optional per the plan; the Windows/Linux polymorphic
_service_status and the disk not-found detection don't map cleanly onto
the new pure functions without risking behavioural drift).
Simone