Add automatic rollback protection on update failure

[purrsec]

• Add signal handling and cleanup trap in omarchy-update-perform
• Validate unified kernel image (UKI) presence after system update
• Automatic snapshot restore if critical boot files are missing
• Detect update interruptions (Ctrl+C, terminal close, etc.)
• Update user message to warn about terminal closure

[purrsec]

Ready to merge ;)

[purrsec]

Ready to merge ;))

[purrsec]

Hey @mghextreme , do you know why it hasn't been merged ? It's been three releases now that it's been overlooked.

[mghextreme]

@purrsec While I did approve the PR, I'm not a maintainer of the project :confused: I just looked at, agreed with it, and left my approval as a recommendation. But it's up to the maintainers like @dhh and @ryanrhughes to actually merge this.