Can't load Windows XP ISO images on M5 Max

**Describe the issue**
I'm currently trying to follow the [Windows XP guide](https://mac.getutm.app/gallery/windows-xp) and am attempting to load the exact Windows ISO to the preconfigured Windows XP VM but am getting this very unhelpful message stating that the ISO "couldn't be loaded". I've mounted it to Finder so I know it's a valid ISO and the SHA1 matches. I even tried an alternative ISO and got the same error. I tried the ISOs in Parallel and they said they aren't compatible with ARM Macs, but UTM supports emulation, so not sure of the issue.

I've tried doing searches on here for similar issues, but all I can find are issues with loading ISOs on iOS/iPadOS.

**Configuration**
* UTM Version: 4.7.5
* macOS Version: 26.6.2
* Mac Chip (Intel, M1, ...): M5 Max

Start by reproducing the failure on macOS 26.6.2 with UTM 4.7.5, the Windows XP guide’s preconfigured VM, and both reported ISO images. Compare the exact load behavior and error, then determine why valid XP ISOs fail on the M5 Max; done means identifying the compatibility issue or documenting the missing requirement and a verified fix.

Written by the indexing model from the issue text.