PLN: "we gotta ensure these are unified proper gig single service or package
easy to maintain/add things to."

tools/rig_units.py is now THE inventory. Three consumers, no re-typing:
the Bridge panel imports SERVICES, gig-up.sh reads --ensure, and
parvagues-rig.target is GENERATED by --target. Same shape as lcxl_grid.py (#97),
for the same reason: the list was previously a hand-typed table in bridge/rig.py
(5 rows, missing parvagues-bridge), a hardcoded loop in gig-up.sh (4 names), and
whatever [Install] each unit carried. Adding a unit to the rig is one row.

Two real bugs closed:

* gig-up.sh only ever ran `systemctl start`, never `enable`. A start fixes
  tonight and changes nothing about the next login — exactly how
  tidal-ardour-autoroute sat `disabled` while every pre-gig check passed.
  --ensure does both verbs, per-unit boot policy: the reconcilers are "login"
  (they idle, hold no ports, make no sound), parvagues-sc stays "on-demand"
  because a login must not start SuperDirt.

* `is-enabled` returning "linked" means NOT enabled — it reads like a healthy
  word. --status says so in words instead of printing systemd term.

Also learned the hard way while doing this: a unit file symlinked from
~/.config/systemd/user into a FEATURE branch vanishes on `git checkout`, and
`systemctl disable` on a linked unit deletes the symlink itself. Live infra
files belong on master; both units are there now.

systemctl --user start parvagues-rig.target  # the single handle