feat: HA-Cluster v1.2.x — Split-Brain, TOTP, Enterprise-FW, Drift-Fix, VIP-Recovery

- keepalived: pg_role='standby' hat Vorrang vor role für BACKUP-Bestimmung
- keepalived-master.sh: gecrasht Dienste beim MASTER-Übergang starten (nicht nur reload)
- confighash: ip_addresses per Interface-Name hashen statt per FK (Cross-Node-Drift-Fix)
- TOTP/2FA: RFC 6238 — Setup-Flow, QR-Code, Admin-Disable; two-step Login
- Firewall-UI: Enterprise-Design — auto-Beschreibung, icon-only Actions, zero-hit Indikator
- fe80-Filter: Link-local IPv6 aus NTP/DNS Listen-Dropdowns entfernen
- VIP-Dashboard, Dual-Path VRRP, GW-Tracking (Migrations 0033/0034)
- Forward Proxy + DNS erweiterte Einstellungen (Migrations 0031/0032)
- unbound-control: edgeguard in unbound-Gruppe via postinst

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/apt-repo/build-package.sh

@@ -81,7 +81,7 @@ build_api() {
     # Keepalived notify-scripts → /usr/lib/edgeguard/
     # postinst setzt chmod 0755 nach der Installation.
     mkdir -p "$build_dir/usr/lib/edgeguard"
-    for script in keepalived-check.sh keepalived-master.sh keepalived-backup.sh; do
+    for script in keepalived-check.sh keepalived-master.sh keepalived-backup.sh keepalived-gw-check.sh; do
         install -m 0755 "$REPO_ROOT/packaging/scripts/$script" \
                         "$build_dir/usr/lib/edgeguard/$script"
     done