Introduces non-server home-manager configs

Allows home-manager configs to be done on a server/non-server basis

Provides an example config by moving emacs to its own space (behind a
lib.optionals so only non-server machines accept it)

marks artemision and rhapsody-in-green as explicitly non-server machines

Signed-off-by: ahuston-0 <aliceghuston@gmail.com>

systems/artemision/default.nix

@@ -3,6 +3,7 @@
   system = "x86_64-linux";
   home = true;
   sops = true;
+  server = false;
   users = [ "alice" ];
   modules = [
     inputs.nixos-hardware.nixosModules.framework-16-7040-amd

systems/rhapsody-in-green/default.nix

@@ -4,5 +4,6 @@
   system = "x86_64-linux";
   home = true;
   sops = true;
+  server = false;
   modules = [ inputs.nixos-hardware.nixosModules.framework-13-7040-amd ];
 }