refactor(#2352): extract standalone hivectl crate, hive-c0re daemon-only

nix/host-modules/hive-c0re/options.nix

@@ -23,8 +23,8 @@
       defaultText = lib.literalExpression "hyperhive.packages.\${system}.default";
       description = ''
         hyperhive workspace package. Provides `/bin/hive-c0re`
-        (coordinator daemon + admin-socket CLI) and `/bin/hivectl`
-        (operator-facing host CLI for ad-hoc administration). Wired to
+        (coordinator daemon) and `/bin/hivectl` (operator-facing host
+        CLI for ad-hoc administration + the host admin socket). Wired to
         this flake's `packages.<system>.default` by
         `nixosModules.default` (via `lib.mkDefault`, so setting it here
         wins).