Fix ARM64 preset conflict: write linux-aarch64.preset in customize_airootfs

Writing the preset to the airootfs overlay caused a file conflict when
pacstrap installed linux-aarch64 (which ships its own copy of the file).
Move the preset override into customize_airootfs.sh which runs after
pacstrap, so the package installs cleanly then we replace the preset.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

iso/docker/entrypoint-arm64.sh

@@ -215,20 +215,6 @@ FILES=()
 HOOKS=(base udev plymouth archiso block filesystems keyboard)
 MKCONF
 
-# mkinitcpio preset for the aarch64 live boot image.
-# mkarchiso looks for a preset named 'archiso' to build the live initramfs.
-# The linux-aarch64 package only ships 'default'/'fallback' presets, so we
-# provide our own with the archiso hooks and the correct kernel path.
-mkdir -p "$AIROOTFS/etc/mkinitcpio.d"
-cat > "$AIROOTFS/etc/mkinitcpio.d/linux-aarch64.preset" <<'PRESET'
-ALL_config="/etc/mkinitcpio.conf.d/archiso.conf"
-ALL_kver="/boot/vmlinuz-linux-aarch64"
-
-PRESETS=('archiso')
-
-archiso_image="/boot/initramfs-linux-aarch64.img"
-PRESET
-
 cat > "$AIROOTFS/etc/hostname" <<'EOF'
 orionos
 EOF
@@ -672,8 +658,19 @@ update-desktop-database 2>/dev/null || true
 fc-cache -f 2>/dev/null || true
 
 plymouth-set-default-theme orionos 2>/dev/null || true
-# Run only the aarch64 preset — mkinitcpio -P would also try linux.preset
-# (which references the x86_64 vmlinuz-linux) and fail.
+
+# Override linux-aarch64.preset with an 'archiso' entry for the live initramfs.
+# Done here (post-pacstrap) to avoid conflicting with the package's own preset
+# file during installation. mkarchiso looks for a preset named 'archiso'.
+cat > /etc/mkinitcpio.d/linux-aarch64.preset <<'PRESET'
+ALL_config="/etc/mkinitcpio.conf.d/archiso.conf"
+ALL_kver="/boot/vmlinuz-linux-aarch64"
+
+PRESETS=('archiso')
+
+archiso_image="/boot/initramfs-linux-aarch64.img"
+PRESET
+
 mkinitcpio -p linux-aarch64 2>&1 | tail -10 || true
 
 mkdir -p /etc/skel