Fix ISO build pipeline for Docker on macOS

- Disable pacman alpm sandbox in Dockerfile (seccomp blocks it in BuildKit)
- Move mkarchiso from RUN to CMD so it runs with --privileged at docker run time
- Fix output path: mkarchiso now writes to /dist (matches volume mount)
- Add syslinux + imlib2 to Docker build packages and live ISO package list
- Copy syslinux/ and efiboot/ boot configs from archiso releng into profile
- Switch deprecated UEFI grub bootmodes to uefi-x64.systemd-boot
- Fix wrong package names: libpam→pam, light→brightnessctl, remove pkexec
- Set SigLevel=Never and hardcode reliable mirrors in profile pacman.conf
- Add mkinitcpio.conf with archiso hook so initrd can mount the live squashfs

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

iso/profile/airootfs/etc/mkinitcpio.conf

@@ -0,0 +1,4 @@
+MODULES=()
+BINARIES=()
+FILES=()
+HOOKS=(base udev microcode archiso block filesystems keyboard)

iso/profile/packages.x86_64

@@ -24,10 +24,12 @@ libxft
 libxfixes
 libxext
 libpng
+imlib2
 dbus
-libpam
+pam
 fontconfig
 freetype2
+syslinux
 
 # Desktop utilities
 feh
@@ -40,14 +42,13 @@ alsa-utils
 pulseaudio
 
 # Brightness
-light
+brightnessctl
 
 # Media playback control
 playerctl
 
 # Arch tools
 pacman-contrib
-pkexec
 polkit
 
 # System tools

iso/profile/pacman.conf

@@ -1,14 +1,21 @@
 [options]
-HoldPkg     = pacman glibc
+HoldPkg      = pacman glibc
 Architecture = auto
 CheckSpace
 ParallelDownloads = 5
+SigLevel     = Never
 
 [core]
-Include = /etc/pacman.d/mirrorlist
+Server = https://geo.mirror.pkgbuild.com/$repo/os/$arch
+Server = https://mirrors.kernel.org/archlinux/$repo/os/$arch
+Server = https://mirror.rackspace.com/archlinux/$repo/os/$arch
 
 [extra]
-Include = /etc/pacman.d/mirrorlist
+Server = https://geo.mirror.pkgbuild.com/$repo/os/$arch
+Server = https://mirrors.kernel.org/archlinux/$repo/os/$arch
+Server = https://mirror.rackspace.com/archlinux/$repo/os/$arch
 
 [multilib]
-Include = /etc/pacman.d/mirrorlist
+Server = https://geo.mirror.pkgbuild.com/$repo/os/$arch
+Server = https://mirrors.kernel.org/archlinux/$repo/os/$arch
+Server = https://mirror.rackspace.com/archlinux/$repo/os/$arch

iso/profile/profiledef.sh

@@ -9,8 +9,7 @@ iso_version="$(date +%Y.%m)"
 install_dir="arch"
 buildmodes=('iso')
 bootmodes=('bios.syslinux.mbr' 'bios.syslinux.eltorito'
-           'uefi-ia32.grub.esp' 'uefi-x64.grub.esp'
-           'uefi-ia32.grub.eltorito' 'uefi-x64.grub.eltorito')
+           'uefi-x64.systemd-boot.esp' 'uefi-x64.systemd-boot.eltorito')
 arch="x86_64"
 pacman_conf="pacman.conf"
 airootfs_image_type="squashfs"