gallery-423-foss-release

本次更新：修复 HDR 视频预览黑条

• HDR 视频在尚未开始播放时不再显示空的 SurfaceView，避免缩略图被黑色横条遮挡
• 只有真正开始播放后才切换到 SurfaceView 进行 HDR 输出
• 版本号更新为 6.28.29 (423)

Fix HDR preview black bar

• Empty SurfaceView is no longer shown before HDR playback starts, so it cannot cover the thumbnail with a black bar
• The HDR surface is revealed only after playback actually begins
• Version 6.28.29 (423)

完整更新记录见 CHANGELOG.md。