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/firacode-install.sh

@@ -1,4 +1,25 @@
 #!/bin/bash
+# 下载 Fira Code 字体压缩包并打开所在目录（需手动安装）
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+# shellcheck disable=SC1091
+source "$SCRIPT_DIR/common/help.sh"
+
+usage() {
+    cat <<'EOF'
+用法: firacode-install
+
+从 GitHub 下载 Fira Code v6.2 到 ~/Downloads/，并打开 Finder/文件管理器。
+需在图形界面中解压并安装字体文件。
+
+选项:
+  -h, --help  显示此帮助
+EOF
+}
+
+dotfile_help_requested "${1:-}" && dotfile_show_help
+
+set -euo pipefail
 
 cd ~/Downloads/
 wget https://github.com/tonsky/FiraCode/releases/download/6.2/Fira_Code_v6.2.zip