GM_update

Refresh tabc_master_database.json from the live TABC green-material website (https://tabcmgr.hopto.org) and re-sync the showcase page's offline cache. Also the first-time bootstrap entry point after a fresh clone — creates both files from scratch if they don't exist yet. Trigger keywords: 更新綠建材資料、更新原始網頁資料、GM_update、refresh TABC database、更新 TABC 資料庫、第一次抓取、初始化綠建材資料庫。