ZFS: dedup toggle per pool and dedup option for new datasets

Pool cards show the dedup ratio and can set dedup=on|off on the pool root
dataset (inherited by children); the new-dataset form gets a dedup option.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/collect/zfs_test.go

@@ -119,6 +119,15 @@ func TestParseZpoolList(t *testing.T) {
 	if pools[1].CapPct != 90 || pools[1].FragPct != 0 {
 		t.Errorf("pool1 = %+v", pools[1])
 	}
+	if pools[0].DedupRatio != 0 {
+		t.Errorf("dedup ratio without the column = %v", pools[0].DedupRatio)
+	}
+
+	// with the dedup column; -p prints "1.35", without -p it is "1.35x"
+	pools = parseZpoolList([]byte("a\t1\t1\t0\t100\tONLINE\t0\t1.35\nb\t1\t1\t0\t100\tONLINE\t0\t2.00x\n"))
+	if len(pools) != 2 || pools[0].DedupRatio != 1.35 || pools[1].DedupRatio != 2 {
+		t.Errorf("dedup ratio = %+v", pools)
+	}
 }
 
 func TestParseZfsList(t *testing.T) {
@@ -127,4 +136,8 @@ func TestParseZfsList(t *testing.T) {
 	if len(ds) != 2 || ds[1].Name != "nas_pool_1_8_gb/appdata" || ds[1].Avail != 200 {
 		t.Errorf("datasets = %+v", ds)
 	}
+	ds = parseZfsList([]byte("tank\t1\t2\t3\t/tank\ton\n"))
+	if len(ds) != 1 || ds[0].Dedup != "on" || ds[0].Mountpoint != "/tank" {
+		t.Errorf("dedup column: %+v", ds)
+	}
 }