新增：GOG 限免提醒（Beta）
回應 #1 的建議。開啟後，GOG 有這兩種免費遊戲時會通知你：
- 首頁限時贈送：附截止時間；登入 GOG 後按首頁橫幅上的按鈕領取
- 折扣到 0 元的遊戲：加入購物車，以 0 元結帳

領到的遊戲會永久留在你的 GOG 遊戲庫。跟 Epic 一樣只提醒、不代領：GOG 的領取需要你的 GOG 登入權杖，而 FreeKeep 從不碰任何登入資料。

• 預設關閉，到設定頁「Epic 與 GOG 提醒」開啟；popup 會多一個 GOG 分頁
• 讀取的是 GOG 公開的首頁與商品目錄，匿名請求，只帶瀏覽器語言，不需要 GOG 帳號
• Beta：加入後 GOG 還沒辦過限時贈送，下一次限免才是第一次實戰。如果限免期間沒收到通知，請按 popup 的「複製診斷報告」並開 Issue 回報

• 新增兩個選用權限 sections.gog.com、catalog.gog.com：只在開啟 GOG 提醒時才請求，關閉就移除；更新時不會出現新的權限警告
• 其餘權限不變，仍然沒有 Cookie、分頁或腳本權限

• Chrome 線上應用程式商店／Firefox 附加元件：審查通過後會自動更新
• 手動安裝（Chromium 瀏覽器）：下載 freekeep-for-steam-0.4.0-chrome.zip，解壓縮後在 chrome://extensions 開啟開發人員模式並載入
• freekeep-for-steam-0.4.0-firefox.zip 是 Firefox 版（可在 about:debugging 暫時載入測試），freekeep-for-steam-0.4.0-sources.zip 是送 Firefox 審查用的原始碼包

New: GOG reminders (beta). Suggested in #1. FreeKeep can now tell you about two kinds of free games on GOG: giveaways on GOG's home page (with their end date; claim them with the button on the home page banner while logged in to GOG) and games discounted to 0 (add to cart and check out for free). Either way the game stays in your GOG library for good. Like Epic, it's reminder-only: claiming on GOG needs your GOG login token, and FreeKeep never touches login data.

Off by default: turn it on under Epic & GOG reminders in the settings, and the popup gets a GOG tab. FreeKeep reads GOG's public home page and catalog anonymously, with only your browser's language, and needs no GOG account.

Beta. No GOG giveaway has run since this was added, so the next one will be its first real test. If one is on and FreeKeep doesn't tell you, please open an issue with Copy diagnostics from the popup.

Permissions. Two new optional permissions, sections.gog.com and catalog.gog.com, requested only when you turn on GOG reminders and removed when you turn them off, so updating shows no new permission warning. Still no cookies, tabs or scripting permissions.