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>

CHANGELOG.md

@@ -35,6 +35,14 @@ All notable changes to Jarl are documented here. The format follows
   and `list` prints the IDs too. With a change (`jarl record add ... -o
   id`) they apply to the changed object.
 
+- Statistics: client lists (busiest and refused clients, in the web UI,
+  `jarl stats top clients|refused` and `jarl stats summary`) show the host
+  name Jarl's records have for each address: the PTR record's target, or
+  else the name of an A/AAAA record. Looked up in Jarl's own data, so no
+  DNS queries; an address without a record shows as before.
+- Zones list: a padlock after each signed zone's name, linking to its
+  DNSSEC tab (open and amber while signing is being turned off).
+
 ### Changed
 
 - The web UI and API can listen on ports below 1024, such as 443: