Enable networking and set the base locale on neogaia

Turn the booted laptop into a usable, remotely reachable console: enable
NetworkManager so wifi can be joined from the console and an SSH daemon so
the rest of the setup can be driven over the network. Set the base locale to
timezone America/New_York, locale en_GB.UTF-8, and console keymap us.

These live inline in the neogaia Host rather than behind enable Modules,
matching the single-Host MVI precedent; a shared locale/networking Module can
be extracted once a second Host needs the same settings. SSH keeps default
password auth on, as first-boot access relies on the hand-set bootstrap
password until key/sops-based auth lands post-install.

hosts/neogaia/default.nix

@@ -28,4 +28,15 @@
 
   # Swap is RAM-backed zram rather than an on-disk partition.
   zramSwap.enable = true;
+
+  # NetworkManager drives the wifi so it can be joined from the console.
+  networking.networkmanager.enable = true;
+
+  # An SSH daemon so the rest of the setup can be driven over the network.
+  services.openssh.enable = true;
+
+  # Locale preferences for the base system.
+  time.timeZone = "America/New_York";
+  i18n.defaultLocale = "en_GB.UTF-8";
+  console.keyMap = "us";
 }