Add overlay installer for existing Omarchy systems

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QKxGW1raAWaqeU8WdHsMsp

bin/omarchy-cn-install-overlay

@@ -0,0 +1,66 @@
+#!/bin/bash
+# omarchy:summary=Install or remove the OmarchyCN layer on an existing Omarchy
+# omarchy:args=[--uninstall]
+# omarchy:examples=omarchy-cn-install-overlay | omarchy-cn-install-overlay --uninstall
+# Bootstraps onto a foreign OMARCHY_PATH, so it resolves its own checkout root.
+
+set -euo pipefail
+
+SRC=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")/.." && pwd)
+DEST="${OMARCHY_PATH:?OMARCHY_PATH must point at the target Omarchy install}"
+MANIFEST="$HOME/.local/state/omarchycn/overlay-manifest"
+
+run_dest() {
+  if [[ -w $DEST ]]; then
+    "$@"
+  else
+    sudo "$@"
+  fi
+}
+
+uninstall() {
+  if [[ ! -f $MANIFEST ]]; then
+    echo "No overlay manifest at $MANIFEST" >&2
+    exit 1
+  fi
+  while IFS= read -r rel; do
+    [[ $rel == source=* ]] && continue
+    run_dest rm -f "$DEST/$rel"
+  done < "$MANIFEST"
+  run_dest rm -rf "$DEST/cn"
+  rm -f "$MANIFEST"
+  echo "OmarchyCN overlay removed from $DEST"
+}
+
+install() {
+  if [[ ! -f $DEST/version || ! -x $DEST/bin/omarchy ]]; then
+    echo "No Omarchy install found at $DEST" >&2
+    exit 1
+  fi
+  if [[ $SRC == "$DEST" ]]; then
+    echo "Source checkout and target are the same tree; nothing to overlay" >&2
+    exit 1
+  fi
+
+  mkdir -p "${MANIFEST%/*}"
+  echo "source=$SRC" > "$MANIFEST"
+
+  run_dest mkdir -p "$DEST/cn"
+  run_dest cp -r "$SRC/cn/." "$DEST/cn/"
+
+  local f rel
+  for f in "$SRC/bin/omarchycn" "$SRC"/bin/omarchy-cn-*; do
+    rel="bin/${f##*/}"
+    run_dest cp "$f" "$DEST/$rel"
+    echo "$rel" >> "$MANIFEST"
+  done
+
+  echo "OmarchyCN overlay installed into $DEST ($(grep -c '^bin/' "$MANIFEST") commands)"
+  echo "Verify: omarchy cn version"
+}
+
+if [[ ${1:-} == "--uninstall" ]]; then
+  uninstall
+else
+  install
+fi