feat: add script catalog and -h help for all dotfile scripts

Introduce ff script -h with auto descriptions, shared help.sh, and usage flags across script/*.sh.

Co-authored-by: Cursor <cursoragent@cursor.com>

script/brew-clean.sh

@@ -1 +1,28 @@
 #!/bin/bash
+# 清理 Homebrew 缓存与无用文件
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+# shellcheck disable=SC1091
+source "$SCRIPT_DIR/common/help.sh"
+
+usage() {
+    cat <<'EOF'
+用法: brew-clean
+
+执行 Homebrew 清理（brew cleanup），删除旧版本与缓存。
+
+选项:
+  -h, --help  显示此帮助
+EOF
+}
+
+dotfile_help_requested "${1:-}" && dotfile_show_help
+
+set -euo pipefail
+
+if ! command -v brew &>/dev/null; then
+    echo "错误: 未找到 brew，请先安装 Homebrew" >&2
+    exit 1
+fi
+
+brew cleanup