Switch install.sh to GNU Stow for symlinking

Manual ln -sfn loop replaced with stow zsh gnupg, matching the repo's
existing per-package-directory convention. Still backs up/removes any
conflicting file or foreign symlink at the target before stowing.

install.sh

@@ -1,19 +1,16 @@
 #!/usr/bin/env bash
-# Bootstraps zsh config on a new machine: symlinks dotfiles into $HOME and
-# clones oh-my-zsh + the custom theme/plugins referenced by .zshrc.
+# Bootstraps dotfiles on a new machine: installs oh-my-zsh + the custom
+# theme/plugins .zshrc expects, then symlinks packages into $HOME via
+# GNU Stow (each top-level dir is a package mirroring $HOME, e.g.
+# zsh/.zshrc -> ~/.zshrc). Add a new package by adding a new top-level dir.
 set -euo pipefail
 
 DOTFILES_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 ZSH_CUSTOM="${ZSH_CUSTOM:-$HOME/.oh-my-zsh/custom}"
 
-link() {
-  local src="$1" dst="$2"
-  if [ -e "$dst" ] && [ ! -L "$dst" ]; then
-    mv "$dst" "$dst.bak.$(date +%s)"
-    echo "Backed up existing $dst"
-  fi
-  ln -sfn "$src" "$dst"
-  echo "Linked $dst -> $src"
+command -v stow >/dev/null || {
+  echo "GNU Stow is required: sudo pacman -S stow (or your distro's equivalent)" >&2
+  exit 1
 }
 
 clone_if_missing() {
@@ -34,14 +31,30 @@ clone_if_missing https://github.com/zsh-users/zsh-history-substring-search "$ZSH
 clone_if_missing https://github.com/zsh-users/zsh-completions "$ZSH_CUSTOM/plugins/zsh-completions"
 clone_if_missing https://github.com/MichaelAquilina/zsh-you-should-use "$ZSH_CUSTOM/plugins/you-should-use"
 
-link "$DOTFILES_DIR/zsh/.zshrc" "$HOME/.zshrc"
-link "$DOTFILES_DIR/zsh/.zshenv" "$HOME/.zshenv"
-link "$DOTFILES_DIR/zsh/.zprofile" "$HOME/.zprofile"
-link "$DOTFILES_DIR/zsh/.p10k.zsh" "$HOME/.p10k.zsh"
+# Stow refuses to link over a real (non-symlink) file, so move any
+# conflicting pre-existing file aside first (e.g. the .zshrc oh-my-zsh's
+# own installer just wrote above).
+stow_package() {
+  local pkg="$1" f rel target
+  while IFS= read -r -d '' f; do
+    rel="${f#"$DOTFILES_DIR/$pkg/"}"
+    target="$HOME/$rel"
+    if [ -L "$target" ]; then
+      rm "$target"
+    elif [ -e "$target" ]; then
+      mkdir -p "$(dirname "$target")"
+      mv "$target" "$target.bak.$(date +%s)"
+      echo "Backed up existing $target"
+    fi
+  done < <(find "$DOTFILES_DIR/$pkg" -type f -print0)
+  stow --dir="$DOTFILES_DIR" --target="$HOME" --restow "$pkg"
+  echo "Stowed $pkg"
+}
 
-mkdir -p "$HOME/.gnupg"
-chmod 700 "$HOME/.gnupg"
-link "$DOTFILES_DIR/gnupg/.gnupg/gpg-agent.conf" "$HOME/.gnupg/gpg-agent.conf"
+mkdir -p "$HOME/.gnupg" && chmod 700 "$HOME/.gnupg"
+
+stow_package zsh
+stow_package gnupg
 gpgconf --kill gpg-agent 2>/dev/null || true
 
 cat <<'EOF'