Same move as grafana, and the three belong together: they derive from one
switch and a store with no UI is as useless as a UI with no store.
`victorialogs` is the case that shows why the option-path sweep is not
enough on its own. It has **zero** references spelled
`swarm.victorialogs.enable` anywhere in the tree, and four spelled
through `let` aliases (`vlCfg.enable` in the collector, `cfg.enable` in
its own module). A sweep for the path would have reported nothing to do
and left every reader broken.
Prose moved with the code rather than being left behind: the comments in
swarm-required-services.nix that explained why the pair derives together
now sit above the assignments that do it, instead of above the gap where
they used to be.