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-install.sh

@@ -1,3 +1,25 @@
+#!/bin/bash
+# 使用国内镜像安装 Homebrew
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+# shellcheck disable=SC1091
+source "$SCRIPT_DIR/common/help.sh"
+
+usage() {
+    cat <<'EOF'
+用法: brew-install
+
+通过中科大镜像安装 Homebrew（设置 HOMEBREW_* 镜像环境变量后执行官方安装脚本）。
+
+选项:
+  -h, --help  显示此帮助
+EOF
+}
+
+dotfile_help_requested "${1:-}" && dotfile_show_help
+
+set -euo pipefail
+
 export HOMEBREW_BREW_GIT_REMOTE="https://mirrors.ustc.edu.cn/brew.git"
 export HOMEBREW_CORE_GIT_REMOTE="https://mirrors.ustc.edu.cn/homebrew-core.git"
 export HOMEBREW_BOTTLE_DOMAIN="https://mirrors.ustc.edu.cn/homebrew-bottles"