feat(update-modal): display last 5 release notes instead of single

- Modified backend to fetch last 5 releases from GitHub API
- Updated frontend to iterate through and display multiple releases
- Added latest badge and publish date styling
- Added update.latestBadge translation key to all locales
- Maintains backward compatibility for single changelog display

locales/zh-TW.json

@@ -1214,6 +1214,7 @@
         "checkingUpdates": "正在檢查更新...",
         "checkingMessage": "請稍候，正在檢查最新版本。",
         "showNotifications": "顯示更新通知",
+        "latestBadge": "最新",
         "updateProgress": {
             "preparing": "正在準備更新...",
             "installing": "正在安裝更新...",