Complete migration of home-manager modules to roles

Migrate all remaining home-manager modules from home/modules/ to home/roles/
to establish a unified role-based configuration pattern. This completes the
migration started in Phase 1.

Changes:
- Phase 1-3: Migrated tmux, plasma-manager, kubectl, and emacs to roles
- Phase 4: Migrated aerospace with custom options under home.roles.aerospace.*
- Phase 5: Migrated i3+sway with shared config and override options
- Phase 6: Removed empty home/modules/ directory

All home configs now import only ./roles with role-based enable options.
Updated flake.nix machine-specific overrides to use new namespaces.

Verified with nix flake check - all configurations build successfully.

home/roles/emacs/default.nix

@@ -0,0 +1,77 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.home.roles.emacs;
+
+  doomEmacs = pkgs.fetchFromGitHub {
+    owner = "doomemacs";
+    repo = "doomemacs";
+    rev = "8f55404781edacf66fa330205533b002de3fb5ee";
+    sha256 = "sha256-vHwgENjip2+AFzs4oZfnKEAJKwf5Zid7fakImvxxQUw=";
+  };
+
+  # Shared emacs packages
+  emacsPackages = epkgs: [
+    epkgs.vterm
+    epkgs.treesit-grammars.with-all-grammars
+  ];
+
+  # Default emacs configuration with vterm support
+  defaultEmacsPackage =
+    if pkgs.stdenv.isDarwin
+    then pkgs.emacs-macport.pkgs.withPackages emacsPackages
+    else pkgs.emacs.pkgs.withPackages emacsPackages;
+in
+{
+  options.home.roles.emacs = {
+    enable = mkEnableOption "Doom Emacs with vterm and tree-sitter support";
+  };
+
+  config = mkIf cfg.enable {
+    home.packages = [
+      pkgs.emacs-all-the-icons-fonts
+      pkgs.fira-code
+      pkgs.fontconfig
+      pkgs.graphviz
+      pkgs.isort
+      pkgs.nerd-fonts.fira-code
+      pkgs.nerd-fonts.droid-sans-mono
+      pkgs.nil # nix lsp language server
+      pkgs.nixfmt-rfc-style
+      (pkgs.ripgrep.override {withPCRE2 = true;})
+      pkgs.pipenv
+      pkgs.poetry
+      pkgs.python3
+    ];
+
+    programs.emacs = {
+      enable = true;
+      package = defaultEmacsPackage;
+    };
+
+    fonts.fontconfig.enable = true;
+
+    # Mount emacs and tree-sitter grammars from nix store
+    home.file = {
+      "${config.xdg.configHome}/emacs".source = doomEmacs;
+    };
+
+    home.sessionPath = [
+      "${config.xdg.configHome}/emacs/bin"
+    ];
+
+    home.sessionVariables = {
+      DOOMDIR = "${config.xdg.configHome}/doom";
+      DOOMLOCALDIR = "${config.xdg.dataHome}/doom";
+    };
+
+    # TODO: Use mkOutOfStoreSymlink instead?
+    home.activation.doomConfig = lib.hm.dag.entryAfter ["writeBoundary"] ''
+      # Always remove and recreate the symlink to ensure it points to the source directory
+      rm -rf "${config.xdg.configHome}/doom"
+      ln -sf "${config.home.homeDirectory}/nixos-configs/home/roles/emacs/doom" "${config.xdg.configHome}/doom"
+    '';
+  };
+}