feat(user): switch primary identity to lyrathorpe / Lyra Thorpe

Thread username and fullName per host through the flake host table and specialArgs / home-manager.extraSpecialArgs, so user.nix and git.nix derive identity instead of hardcoding it.

MBP and X1 now provision user lyrathorpe (Lyra Thorpe). EDaaS retains emmathorpe (Emma Thorpe) and its wsl.defaultUser; work commit email is unchanged.

emmathorpe/user.nix

@@ -3,15 +3,17 @@
   pkgs,
   inputs,
   lib,
+  username,
+  fullName,
   ...
 }:
 
 {
   programs.zsh.enable = true;
-  users.users.emmathorpe = {
+  users.users.${username} = {
     isNormalUser = true;
-    home = "/home/emmathorpe";
-    description = "Emma Thorpe";
+    home = "/home/${username}";
+    description = fullName;
     extraGroups = [
       "wheel"
       "docker"