feat(home): theme CLI tools, add staples, env defaults and mime apps

- Catppuccin Mocha for fzf (colors), bat (catppuccin/bat tmTheme) and
  git delta (syntax-theme + navigate/line-numbers/side-by-side).
- CLI staples on every host: ripgrep, fd, jq, btop, plus gh (SSH) and
  tea (Gitea CLI).
- home.sessionVariables: PAGER, MANPAGER (bat), VISUAL; xdg.enable.
- xdg.mimeApps defaults (web->Firefox, directories->nemo).
- Document the stateVersion pin. README updated.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

system/modules/work/default.nix

@@ -1,53 +0,0 @@
-{ pkgs, lib, ... }:
-
-{
-  # The work box keeps its own (corporate) ~/.ssh/config; don't let the personal
-  # programs.ssh (shell.nix) take it over. The ssh-agent below still runs.
-  programs.ssh.enable = lib.mkForce false;
-
-  programs.git = {
-    settings = {
-      commit.gpgsign = true;
-      tag.gpgsign = true;
-      gpg.format = "ssh";
-      user.signingkey = "key::ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIAJMVgeRKnfX1G8coU3nAobI485aeUpGTMqH7+zbKI8o emma.thorpe@cloud.com";
-      user.email = "emma.thorpe@citrix.com";
-    };
-  };
-  home.packages = [
-    pkgs.kubectl
-    pkgs.argo-rollouts
-    pkgs.tenv
-    pkgs.kubernetes-helm
-    pkgs.azure-cli
-    pkgs.kubelogin
-    pkgs.curl
-    pkgs.notation
-    pkgs.powershell
-    pkgs.nuget
-    pkgs.gedit
-    pkgs.lens
-    pkgs.python3
-    pkgs.gnumake
-    pkgs.gcc
-    pkgs.libiconv
-    pkgs.autoconf
-    pkgs.automake
-    pkgs.pkg-config
-    pkgs.wget
-    pkgs.claude-code
-    pkgs.google-cloud-sdk
-  ];
-  services.ssh-agent.enable = true;
-  home.shellAliases = {
-    docker = "/run/current-system/sw/bin/docker";
-  };
-  programs.tmux = {
-    extraConfig = ''
-      			set -g status-right "#(/run/current-system/sw/bin/bash $HOME/code/kube-tmux/kube.tmux 250 red black)"		
-    '';
-  };
-  programs.go = {
-    enable = true;
-  };
-}