Add DNS monitoring and refresh functionality

Introduce DNS monitoring: add DnsService (comprehensive DNS lookup, crt.sh discovery, Cloudflare detection, IP enrichment) and a new DnsRecord model to persist snapshots, manage diffs, and provide queries/stats. Update DomainController to support a dns_monitoring_enabled flag, refactor WHOIS/DNS refresh logic into performWhoisRefresh/performDnsRefresh, and add endpoints for refreshWhois, refreshDns and refreshAll; send notifications when DNS monitoring is toggled. Add UI templates/tabs for DNS, billing, notifications, overview, SSL and WHOIS and wire DNS data into the domain view; expose cached IP details. Add cron/check_dns.php and migration 027_add_dns_monitoring.sql (and include it in installer migration lists). Other tweaks: safer EmailHelper subject handling, TldRegistry search improvements, domain sorting using an effective status (expiring_soon), Discord channel null-safe fields, settings UI additions (domain_view_template and cron staleness warnings), and route/migration updates. This enables scheduled and manual DNS scans with persistent records and notifications.

app/Controllers/InstallerController.php

@@ -57,6 +57,7 @@ class InstallerController extends Controller
             '024_add_status_notifications_v1.1.2.sql',
             '025_add_update_system_v1.1.3.sql',
             '026_update_app_version_v1.1.4.sql',
+            '027_add_dns_monitoring.sql',
         ];
         
         try {
@@ -200,6 +201,7 @@ class InstallerController extends Controller
                     '024_add_status_notifications_v1.1.2.sql',
                     '025_add_update_system_v1.1.3.sql',
                     '026_update_app_version_v1.1.4.sql',
+                    '027_add_dns_monitoring.sql',
                 ];
             }
             
@@ -423,6 +425,7 @@ class InstallerController extends Controller
                     '024_add_status_notifications_v1.1.2.sql',
                     '025_add_update_system_v1.1.3.sql',
                     '026_update_app_version_v1.1.4.sql',
+                    '027_add_dns_monitoring.sql',
                 ];
                 
                 $stmt = $pdo->prepare("INSERT INTO migrations (migration) VALUES (?) ON DUPLICATE KEY UPDATE migration=migration");