Replace GRUB with ZFSBootMenu bootloader

This is a major change that replaces the GRUB bootloader with ZFSBootMenu,
providing native ZFS boot environment support.

Key changes:
- EFI partition reduced from 1GB to 512MB (only holds ZFSBootMenu)
- EFI now mounts at /efi instead of /boot
- Kernel and initramfs live on ZFS root (enables snapshot boot with matching kernel)
- Downloads pre-built ZFSBootMenu EFI binary from get.zfsbootmenu.org
- Creates EFI boot entries for all disks in multi-disk configurations
- Syncs ZFSBootMenu to all EFI partitions for redundancy
- Sets org.zfsbootmenu:commandline on zroot/ROOT for kernel cmdline inheritance
- Sets bootfs pool property for default boot environment
- AMD GPU workarounds (pg_mask, cwsr_enable) added to kernel cmdline when AMD detected

Deleted GRUB snapshot tooling (no longer needed):
- custom/grub-zfs-snap
- custom/40_zfs_snapshots
- custom/zz-grub-zfs-snap.hook
- custom/zfs-snap-prune

Updated helper scripts:
- zfssnapshot: removed grub-zfs-snap call, shows ZFSBootMenu tip
- zfsrollback: removed grub-zfs-snap call, notes auto-detection

Tested configurations:
- Single disk installation
- 2-disk mirror (mirror-0)
- 3-disk RAIDZ1 (raidz1-0)
- All boot correctly with ZFSBootMenu

1 files changed, 0 insertions, 17 deletions

diff --git a/build.sh b/build.sh
index 337564f..acfecd6 100755
--- a/build.sh
+++ b/build.sh
@@ -372,17 +372,6 @@ cp "$CUSTOM_DIR/install-archzfs" "$PROFILE_DIR/airootfs/usr/local/bin/"
 cp "$CUSTOM_DIR/install-claude" "$PROFILE_DIR/airootfs/usr/local/bin/"
 cp "$CUSTOM_DIR/archsetup-zfs" "$PROFILE_DIR/airootfs/usr/local/bin/"
 
-# Copy grub-zfs-snap for ZFS snapshot boot entries
-info "Copying grub-zfs-snap..."
-cp "$CUSTOM_DIR/grub-zfs-snap" "$PROFILE_DIR/airootfs/usr/local/bin/"
-mkdir -p "$PROFILE_DIR/airootfs/usr/local/share/grub-zfs-snap"
-cp "$CUSTOM_DIR/40_zfs_snapshots" "$PROFILE_DIR/airootfs/usr/local/share/grub-zfs-snap/"
-cp "$CUSTOM_DIR/zz-grub-zfs-snap.hook" "$PROFILE_DIR/airootfs/usr/local/share/grub-zfs-snap/"
-
-# Copy zfs-snap-prune for snapshot retention
-info "Copying zfs-snap-prune..."
-cp "$CUSTOM_DIR/zfs-snap-prune" "$PROFILE_DIR/airootfs/usr/local/bin/"
-
 # Copy zfssnapshot and zfsrollback for ZFS management
 info "Copying zfssnapshot and zfsrollback..."
 cp "$CUSTOM_DIR/zfssnapshot" "$PROFILE_DIR/airootfs/usr/local/bin/"
@@ -409,12 +398,6 @@ if grep -q "file_permissions=" "$PROFILE_DIR/profiledef.sh"; then
         /)/ i\  ["/usr/local/bin/archsetup-zfs"]="0:0:755"
     }' "$PROFILE_DIR/profiledef.sh"
     sed -i '/^file_permissions=(/,/)/ {
-        /)/ i\  ["/usr/local/bin/grub-zfs-snap"]="0:0:755"
-    }' "$PROFILE_DIR/profiledef.sh"
-    sed -i '/^file_permissions=(/,/)/ {
-        /)/ i\  ["/usr/local/bin/zfs-snap-prune"]="0:0:755"
-    }' "$PROFILE_DIR/profiledef.sh"
-    sed -i '/^file_permissions=(/,/)/ {
         /)/ i\  ["/usr/local/bin/zfssnapshot"]="0:0:755"
     }' "$PROFILE_DIR/profiledef.sh"
     sed -i '/^file_permissions=(/,/)/ {