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/web/static/assets/style.css

@@ -141,6 +141,8 @@ th { font-size: 12px; color: var(--muted); font-weight: 600; text-transform: upp
 tr:hover td { background: var(--info-soft); }
 td.data { font-family: var(--mono); font-size: 13px; word-break: break-all; }
 td.name { font-family: var(--mono); font-size: 13px; white-space: nowrap; }
+a.dnssec-lock { display: inline-flex; vertical-align: -1px; margin-left: 6px; color: var(--ok); text-decoration: none; }
+a.dnssec-lock.off { color: var(--warn); }
 tr.same-name-next td { border-bottom-color: color-mix(in srgb, var(--border) 40%, transparent); }
 td.actions-cell { white-space: nowrap; text-align: right; width: 1%; }
 tr.editing td { background: var(--accent-soft); }