fix(zfs): skip zpool list when /dev/zfs unavailable in Linux (#2325)

Co-authored-by: henrygd <hank@henrygd.me>

agent/zfs/zfs_nonlinux.go

@@ -0,0 +1,9 @@
+//go:build !linux
+
+package zfs
+
+// The /dev/zfs probe is Linux-specific. Other platforms detect availability
+// through the ZFS utilities themselves.
+func checkZfsDevice() error {
+	return nil
+}