feat(docs): add CLAUDE.md for repository guidance and configuration details

CLAUDE.md

@@ -0,0 +1,61 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with
+code in this repository.
+
+## Overview
+
+Personal dotfiles repository for macOS and Linux. Configuration files are
+symlinked to `$HOME` with a `.` prefix (e.g., `zshrc` becomes `~/.zshrc`).
+
+## Commands
+
+### Installation
+
+```sh
+./install.sh           # Install symlinks and initialize shell
+./install.sh symlinks  # Only install symlinks
+./install.sh terminfo  # Install terminfo entries
+./install.sh launch-agents  # Install macOS LaunchAgents
+```
+
+### Nix packages
+
+```sh
+nix-env -if ~/.dotfiles/default.nix  # Install/update global Nix packages
+nix flake update                      # Update nixpkgs lock
+```
+
+### Hammerspoon
+
+```sh
+cd hammerspoon && make install  # Fetch Spoons and dependencies
+cd hammerspoon && make update   # Update all dependencies
+```
+
+## Structure
+
+- `install.sh` - Main installer, manages symlinks to `$HOME`
+- `flake.nix` / `default.nix` - Nix package management (nixfmt, nil LSP)
+- `zshrc` / `zshenv` / `zprofile` - ZSH configuration entry points
+- `zsh/` - Modular ZSH configs loaded by topic (aliases, kubernetes, golang,
+  etc.)
+- `zsh/zshrc.funcs.zsh` - Helper functions used throughout ZSH config
+- `bin/` - Personal scripts added to PATH
+- `config/` - XDG config files (ghostty, kitty, mise, starship, etc.)
+- `hammerspoon/` - macOS automation with Hammerspoon
+- `tmux/` - Tmux config and plugins (git submodules)
+- `private/` - Private dotfiles (separate repo, gitignored)
+
+## Shell Setup
+
+- Uses [zinit](https://github.com/zdharma-continuum/zinit) for ZSH plugin
+  management
+- Uses [mise](https://mise.jdx.dev/) for runtime version management
+- Uses [starship](https://starship.rs/) for prompt
+- PATH construction happens in `zshenv`, interactive setup in `zshrc`
+
+## Code Style
+
+Shell scripts: 2-space indent, bash-style (see `.editorconfig` for shfmt
+settings).