[Bug]: Ebook and archive thumbnail renderers are case-sensitive

[Sola-ris]

Checklist

• I am using an up-to-date version.
• I have read the documentation.
• I have searched existing issues.

TagStudio Version

HEAD

Operating System & Version

Linux DESKTOP-05R4602 6.18.33.2-microsoft-standard-WSL2 #1 SMP PREEMPT_DYNAMIC Thu Jun 18 21:54:43 UTC 2026 x86_64 GNU/Linux

Description

The thumbnail renderers for archives and ebooks don't work if all images or the one specified in the ComicInfo.xml have their extension in upper case

Expected Behavior

The renderers should be case-insensitive

Steps to Reproduce

1. Add to a library samples.zip
2. Observe a lack of thumbnails for the files

Logs

No response