Mark signed zones with a padlock, and name clients in statistics

The zones list shows a padlock after signed zones, linking to their
DNSSEC tab. Client lists in the statistics show the host name Jarl's
records have for each address (PTR, else A/AAAA); no DNS queries.

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

internal/server/stats_test.go

@@ -58,6 +58,17 @@ func TestStatsAPI(t *testing.T) {
 	if len(tops) != 2 || tops[0]["key"] != "www.example.com" {
 		t.Errorf("top names = %v", tops)
 	}
+	// Clients get the host name of Jarl's record for their address.
+	if c := e.list("/stats/top?kind=client&since=2h", e.token); len(c) != 1 || c[0]["name"] != nil {
+		t.Errorf("unnamed client = %v", c)
+	}
+	e.do("POST", "/zones", e.token, map[string]any{"name": "example.com", "records": []map[string]any{{"name": "ns1", "type": "A", "data": "192.0.2.1"}, {"name": "laptop", "type": "A", "data": "10.0.0.7"}}}, 201)
+	if c := e.list("/stats/top?kind=client&since=2h", e.token); len(c) != 1 || c[0]["name"] != "laptop.example.com" {
+		t.Errorf("named client = %v", c)
+	}
+	if sum := e.do("GET", "/stats/summary?since=2h", e.token, nil, 200); sum["tops"].(map[string]any)["client"].([]any)[0].(map[string]any)["name"] != "laptop.example.com" {
+		t.Errorf("summary clients = %v", sum["tops"])
+	}
 	if b := e.list("/stats/breakdown?group=zone&since=1h", e.token); len(b) != 2 || b[0]["key"] != "example.com" {
 		t.Errorf("zones = %v", b)
 	}