feat: add Home Manager refactoring plan and initial structure

- Add comprehensive Home Manager refactoring plan document
- Create initial Home Manager directory structure with user configs
- Add modular Emacs configuration for Home Manager integration
- Update system configurations for Home Manager compatibility
- Preserve existing functionality while preparing for migration

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

home-manager/users/sma/home.nix

@@ -0,0 +1,42 @@
+# Main home configuration for user 'sma' (admin user)
+# Minimal configuration for system administration tasks
+
+{ config, lib, pkgs, ... }:
+
+{
+  # Home Manager needs a bit of information about you and the paths it should manage
+  home.username = "sma";
+  home.homeDirectory = "/home/sma";
+
+  # This value determines the Home Manager release that your configuration is compatible with
+  home.stateVersion = "25.05";
+
+  # Let Home Manager install and manage itself
+  programs.home-manager.enable = true;
+
+  # Admin-specific packages
+  home.packages = with pkgs; [
+    # System administration tools
+  ];
+
+  # Basic shell configuration
+  programs.zsh = {
+    enable = true;
+    history = {
+      size = 5000;
+      path = "$HOME/.histfile";
+    };
+  };
+
+  # Basic git configuration
+  programs.git = {
+    enable = true;
+    userName = "System Admin";
+    userEmail = "admin@example.com";
+  };
+
+  # Admin-specific environment variables
+  home.sessionVariables = {
+    EDITOR = "nano";
+  };
+}