Duplicate "Omarchy" boot entry boots the image build's stale kernel (machine-id mismatch) #426

What's wrong?

A freshly installed guest shows two Limine menu entries both labelled "Omarchy", and the first one
boots a stale kernel/initramfs left over from image build:

/boot/b6fa37cb3a8447379bea01a831cad782/linux-omarchy/vmlinuz      (image-build machine-id)
/boot/b6fa37cb3a8447379bea01a831cad782/linux-omarchy/initramfs
/etc/machine-id = d7dd55376e674d79a784aa85e162bf36                (machine-id after first boot)

FIND_BOOTLOADERS=yes (from omarchy-defaults.conf) makes limine-entry-tool scan /boot/<machine-id>/,
so the build-time directory becomes a real boot entry. The generated menu then contains:

/+Omarchy
  //linux-omarchy
  protocol: linux
  module_path: boot():/b6fa37.../linux-omarchy/initramfs   <- stale image
  ...
/+Omarchy
  //linux-omarchy
  protocol: efi
  path: boot():/EFI/Linux/omarchy_linux-omarchy.efi        <- current UKI

Both share the same displayed name, and the stale one is listed first, so default_entry: 2 is
needed for a normal boot.

Why this matters for bug reports: any change to the current image (kernel modules, initramfs contents,
boot splash) silently does nothing when the stale entry is picked. While debugging the missing boot
splash I rebooted four times in a row and only later noticed that half of them had booted the old
image, which made the fix look ineffective.

Fix

• Image build: remove /boot/<build-machine-id>/ (or generate the tree under the machine-id the guest
  will end up with) so the shipped image has a single entry.
• Or have the entry generator ignore /boot/<machine-id>/ directories whose machine-id is not the
  running one.

System details

• Try Omarchy 0.1.0-33, Omarchy 4.0.0.r7314.g58858ae-1
• limine 12.9.4, limine-mkinitcpio-hook 1.40.0, FIND_BOOTLOADERS=yes, ENABLE_UKI=yes