Fix unbootable installs: lay the kernel into the target and own GRUB

archiso keeps vmlinuz/initramfs in the ISO boot dir, not the squashfs, so
unpackfs lays down an empty /boot. The chroot's mkinitcpio/grub-mkconfig had
nothing to work with and the ESP ended up empty (firmware found no bootloader).

- shellprocess@kernel (dontChroot) copies the live kernel into the target
  /boot before the bootloader step
- post-install.sh now runs grub-install itself, including a --removable pass
  so firmware with no NVRAM entry still boots via EFI/BOOT/BOOTX64.EFI

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

iso/airootfs/etc/calamares/modules/shellprocess-kernel.conf

@@ -0,0 +1,8 @@
+---
+# Lay the kernel into the target /boot before the bootloader/initramfs steps.
+# Runs in the live environment (not the chroot) so it can read the ISO boot dir.
+dontChroot: true
+timeout: 60
+
+script:
+    - "/usr/bin/bash /usr/local/bin/bos-copy-kernel ${ROOT}"

iso/airootfs/etc/calamares/post-install.sh

@@ -35,7 +35,26 @@ fallback_options="-S autodetect"
 PRESET
 mkinitcpio -P || echo "WARN: mkinitcpio regeneration failed"
 
-# Refresh GRUB so it references the rebuilt initramfs (and the new fallback).
+# ---------------------------------------------------------------------------
+# Install GRUB ourselves. Calamares' bootloader module runs before the kernel
+# and initramfs exist (archiso keeps them out of the squashfs; shellprocess
+# @kernel only lays vmlinuz down just beforehand), so its grub-install/config
+# leaves the ESP empty. Redo it here, now that /boot is fully populated.
+#
+# Two passes: the standard NVRAM entry, plus a --removable copy to
+# EFI/BOOT/BOOTX64.EFI so firmware that lost/never wrote an NVRAM entry (the
+# "no boot device / screen just refreshes" failure) still finds a bootloader.
+# ---------------------------------------------------------------------------
+if command -v grub-install &>/dev/null; then
+    grub-install --target=x86_64-efi --efi-directory=/boot/efi \
+        --bootloader-id=BOS --recheck \
+        || echo "WARN: grub-install (nvram) failed"
+    grub-install --target=x86_64-efi --efi-directory=/boot/efi \
+        --removable --recheck \
+        || echo "WARN: grub-install (removable) failed"
+fi
+
+# Refresh GRUB so it references the kernel + rebuilt initramfs.
 if command -v grub-mkconfig &>/dev/null; then
     grub-mkconfig -o /boot/grub/grub.cfg || echo "WARN: grub-mkconfig failed"
 fi

iso/airootfs/etc/calamares/settings.conf

@@ -1,6 +1,13 @@
 ---
 modules-search: [/etc/calamares/modules, /usr/lib/calamares/modules]
 
+# Second shellprocess instance: copies the live kernel into the target /boot
+# (archiso keeps it out of the squashfs) before the bootloader step runs.
+instances:
+- id: kernel
+  module: shellprocess
+  config: shellprocess-kernel.conf
+
 sequence:
   - show:
     - welcome
@@ -22,6 +29,7 @@ sequence:
     - networkcfg
     - hwclock
     - packages
+    - shellprocess@kernel
     - bootloader
     - shellprocess
     - umount