Follow-up to HexLab98's fix. The sync-before-regenerate invariant was
enforced by convention across 6 callsites (~3 idempotent unit-file reads
per command). Consolidate it into the one function every compare/regenerate
path funnels through — systemd_unit_is_current — and drop the now-redundant
callsite pre-syncs in refresh_systemd_unit_if_needed / systemd_start /
systemd_restart / systemd_status.
Kept the systemd_install pre-sync: the --force path bypasses the
is_current gate and calls generate_systemd_unit() directly, so it needs
its own sync to avoid baking /root/.hermes under sudo.
Reworked the two callsite-ordering tests into a chokepoint-invariant guard
(test_is_current_syncs_before_reading_unit) + a delegation test proving
start/restart no longer pre-sync. Both fail if the chokepoint sync is
removed; the pre-existing behavior test still passes.
kshitijk4poor
d54a8f7079