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.

database/migrations/000_initial_schema_v1.1.0.sql

@@ -141,6 +141,7 @@ CREATE TABLE IF NOT EXISTS domains (
     updated_date DATE,
     abuse_email VARCHAR(255),
     last_checked TIMESTAMP NULL,
+    dns_last_checked TIMESTAMP NULL,
     status ENUM('active', 'expiring_soon', 'expired', 'error', 'available', 'redemption_period', 'pending_delete') DEFAULT 'active',
     whois_data JSON,
     notes TEXT,
@@ -341,6 +342,32 @@ CREATE TABLE IF NOT EXISTS tld_import_logs (
     INDEX idx_status (status)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
 
+-- =====================================================
+-- DNS MONITORING
+-- =====================================================
+
+-- DNS records table for tracking DNS record changes
+CREATE TABLE IF NOT EXISTS dns_records (
+    id INT AUTO_INCREMENT PRIMARY KEY,
+    domain_id INT NOT NULL,
+    record_type VARCHAR(10) NOT NULL COMMENT 'A, AAAA, MX, TXT, NS, CNAME, SOA',
+    host VARCHAR(255) NOT NULL DEFAULT '@',
+    value TEXT NOT NULL,
+    ttl INT NULL,
+    priority INT NULL COMMENT 'MX priority',
+    is_cloudflare BOOLEAN DEFAULT FALSE,
+    raw_data JSON NULL COMMENT 'Full record data from dns_get_record()',
+    first_seen_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    last_seen_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+    FOREIGN KEY (domain_id) REFERENCES domains(id) ON DELETE CASCADE,
+    INDEX idx_domain_id (domain_id),
+    INDEX idx_record_type (record_type),
+    INDEX idx_domain_type (domain_id, record_type),
+    INDEX idx_last_seen (last_seen_at)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+
 -- =====================================================
 -- SYSTEM SETTINGS
 -- =====================================================
@@ -397,6 +424,13 @@ INSERT INTO settings (setting_key, setting_value, `type`, `description`) VALUES
 -- User isolation settings
 ('user_isolation_mode', 'shared', 'string', 'User data visibility mode: shared (all users see all data) or isolated (users see only their own data)'),
 
+-- Domain view settings
+('domain_view_template', 'detailed', 'string', 'Domain view template: detailed or default'),
+
+-- DNS monitoring settings
+('dns_check_interval_hours', '24', 'string', 'DNS record check interval in hours'),
+('last_dns_check_run', NULL, 'datetime', 'Last time DNS cron job ran'),
+
 -- Update system settings
 ('update_channel', 'stable', 'string', 'Update channel: stable (releases only) or latest (releases + hotfixes)'),
 ('update_badge_enabled', '1', 'string', 'Show update available badge in top menu when an update is available (1=yes, 0=no)')