refactor: delete old Ansible configuration

- Remove the Ansible files.
- Move the Nix files to the root level of the repository.

Refs: #39

home-manager/modules/zsh.nix

@@ -0,0 +1,52 @@
+{ config, pkgs, lib, libs, ... }:
+{
+  programs.zsh = {
+    enable = true;
+    enableCompletion = false;
+    dotDir = ".config/zsh";
+
+    shellAliases = {
+      fetch = "git fetch --all --jobs=4 --progress --prune";
+      run = "./run";
+      pull = "git pull --autostash --jobs=4 --summary origin";
+      rebase = "git rebase --autostash --stat";
+      update = "fetch && rebase";
+    };
+
+    initExtra = ''
+      if [ -f ~/.config/zsh/.p10k.zsh ]; then
+        . ~/.config/zsh/.p10k.zsh
+      fi
+
+      eval "$(zoxide init zsh)"
+
+      # Case insensitive autocompletion.
+      zstyle ":completion:*" matcher-list "" "m:{a-zA-Z}={A-Za-z}" "r:|=*" "l:|=* r:|=*"
+      autoload -Uz compinit && compinit
+
+      # No arguments: `git status`
+      # With arguments: acts like `git`
+      g() {
+        if [[ $# -gt 0 ]]; then
+          git "$@"
+        else
+          git status
+        fi
+      }
+
+      compdef g=git
+    '';
+
+    zplug = {
+      enable = true;
+
+      plugins = [
+        { name = "mollifier/cd-gitroot"; }
+        { name = "romkatv/powerlevel10k"; tags = [ as:theme depth:1 ]; }
+        { name = "zsh-users/zsh-autosuggestions"; }
+        { name = "zsh-users/zsh-completions"; }
+        { name = "zsh-users/zsh-syntax-highlighting"; }
+      ];
+    };
+  };
+}