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/home/git.nix

@@ -1,6 +1,6 @@
 # Version control: git + delta pager + commitizen. The work host layers
 # commit signing and an email override on top (see work/default.nix).
-{ pkgs, ... }:
+{ pkgs, fullName, ... }:
 {
   home.packages = [
     pkgs.commitizen
@@ -10,7 +10,7 @@
     enable = true;
     package = pkgs.gitFull;
     settings = {
-      user.name = "Emma Thorpe";
+      user.name = fullName;
       push = {
         autoSetupRemote = true;
       };