Better error messages for enhanced-img

[benmccann]

Describe the bug

https://bsky.app/profile/rich-harris.dev/post/3m444jlvqx22f

Reproduction

User was trying to import .JPG images and we only support .jpg images currently

Logs

System Info

n/a

Severity

annoyance

Additional Information

No response

[benmccann]

#14845 fixes the worst of this

We should probably have a separate warning if you try to enhance a non-supported image type. I.e. one not listed in https://github.com/JonasKruckenberg/imagetools/blob/37b4ccfa7e6c175b098246964cbb3d34bf25d431/packages/vite/src/index.ts#L37