[Windows] fix for detail thumbnail exit

Brief summary

the feature added detail thumbnail #176 opens the images from cover and the backdrop, but can't be closed by the mouse click. i have tried several detail pages and the escape 'ESC' button is the only option to close the thumbnail viewer.

@MiaoMint need the fix to mouse click over image or click outside the image to exit the image viewer.

Steps to reproduce

1. open any content detail page at any extension
2. open the cover or backdrop by mouse click
3. doesn't able to close by mouse click

Miru version

https://github.com/miru-project/miru-app/actions/runs/7548382074

Device

Lenovo ideapad (Windows 10)

Acknowledgements

• I have searched the existing issues and this is a new ticket, NOT a duplicate or related to another open issue.
• If this is an issue with a extension, I should be opening an issue in the extension repository.