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/dotfiles/emacs/init.el

@@ -0,0 +1,3 @@
+# Placeholder for Emacs init.el
+# This will contain the migrated Emacs configuration
+# from dotfiles/geir/emacs-config/init-nix.el

home-manager/dotfiles/emacs/modules/claude-code.el

@@ -0,0 +1,2 @@
+;; Placeholder for Emacs claude-code module
+;; This will contain the migrated claude-code configuration

home-manager/dotfiles/emacs/modules/completion.el

@@ -0,0 +1,2 @@
+;; Placeholder for Emacs completion module
+;; This will contain the migrated completion configuration

home-manager/dotfiles/emacs/modules/development.el

@@ -0,0 +1,2 @@
+;; Placeholder for Emacs development module
+;; This will contain the migrated development configuration

home-manager/dotfiles/emacs/modules/elisp-development.el

@@ -0,0 +1,2 @@
+;; Placeholder for Emacs elisp development module
+;; This will contain the migrated elisp development configuration

home-manager/dotfiles/emacs/modules/navigation.el

@@ -0,0 +1,2 @@
+;; Placeholder for Emacs navigation module
+;; This will contain the migrated navigation configuration

home-manager/dotfiles/emacs/modules/ui.el

@@ -0,0 +1,2 @@
+;; Placeholder for Emacs UI module
+;; This will contain the migrated UI configuration