deploy: rename enableAllLocalDefaults to deploy.singleHostSwarm

Same defect as the switch below it, one tier up: it sat at the TOP of
`services.hyperhive`, a namespace that is meant to be everything about
hyperhive rather than the settings of a single hive. Whether this box is
the whole deployment is as per-host as a decision gets.

The name follows mara's sentence for what it means — "everything in the
swarm is running on this host" — rather than naming its mechanism.
"Defaults" was doing no work: it is not a defaults toggle, it is a claim
about where the swarm lives, and the pair now reads as the containment it
already was, singleHostSwarm implying allSwarmServices plus this hive.

One site was a setter rather than a reference: module-eval's `allLocal`
fixture passes an attrset merged into `services.hyperhive`, so its key
carries the path and had to become `deploy.singleHostSwarm`. A rename by
bare identifier is right for the twelve prose mentions and wrong for
exactly this one, which is worth knowing before the next rename.

nix/host-modules/swarm-controller.nix

@@ -240,7 +240,7 @@ in
     };
 
     # `enable` moved to `services.hyperhive.deploy.swarm-controller.enable` — see
-    # ./deploy.nix. `services.hyperhive.enableAllLocalDefaults` still
+    # ./deploy.nix. `services.hyperhive.deploy.singleHostSwarm` still
     # asserts it, and that was never an exception to "not derived from
     # services.hyperhive.enable": that mode says "this box is the whole
     # deployment", which answers the topology question outright, where
@@ -320,7 +320,7 @@ in
           Empty means unset, which the assertion below refuses — a
           controller with no queue is not a lighter controller.
 
-          `enableAllLocalDefaults` fills this in with loopback, because
+          `singleHostSwarm` fills this in with loopback, because
           that address is only correct when the queue is on this host:
           its container shares the host netns. That derivation lives with
           the mode rather than here, so this option describes itself
@@ -354,7 +354,7 @@ in
           The controller cannot mint its own — minting happens inside
           authelia's state directory during its first boot — so away from
           that host the operator places the secret and names it here.
-          `enableAllLocalDefaults` points this at the minted file, which
+          `singleHostSwarm` points this at the minted file, which
           is exactly the case where one exists locally.
 
           Read by `LoadCredential`, so it needs to be readable by root at