[xianjianlf2]

Summary

• keep GOG library entries when GamesDB metadata is unavailable after retries
• fall back to the existing GOG product API for title, artwork, description, installability, and platform metadata
• preserve the existing behavior for GamesDB entries that are not visible library games
• add unit coverage for product metadata conversion

Fixes #5797

Validation

• pnpm test:ci (22 suites, 136 tests)
• pnpm codecheck
• pnpm exec prettier --check src/backend/storeManagers/gog/library.ts src/backend/storeManagers/gog/unified_info.ts src/backend/storeManagers/gog/tests/unified_info.test.ts
• git diff --check

[flavioislima]

All contributors have signed the CLA ✍️ ✅
_{Posted by the CLA Assistant Lite bot.}

[xianjianlf2]

Thank you for your submission, we really appreciate it. Like many open-source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution. You can sign the CLA by just posting a Pull Request Comment same as the below format.感谢您的提交，我们非常感激。与许多开源项目一样，我们要求您在提交贡献之前签署我们的贡献者许可协议 (CLA) 。您只需按照以下格式在 Pull Request 中发表评论即可签署 CLA。

I have read the CLA Document and I hereby sign the CLA我已阅读 CLA 文件，并在此签署 CLA 文件。

You can retrigger this bot by commenting recheck in this Pull Request. Posted by the CLA Assistant Lite bot.

I have read the CLA Document and I hereby sign the CLA

[flavioislima]

@xianjianlf2 you really just need to answer with that text

[xianjianlf2]

I have read the CLA Document and I hereby sign the CLA

[xianjianlf2]

recheck

[xianjianlf2]

已同步最新 upstream/main（原分支落后 3 个提交）并重新验证。全量 test:ci 22 suites / 136 tests 通过；codecheck 通过；改动文件 Prettier 通过。请维护者 review。

[flavioislima]

Thanks @xianjianlf2