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>

internal/database/migrations/0031_forward_proxy_settings.sql

@@ -0,0 +1,25 @@
+-- +goose Up
+-- +goose StatementBegin
+
+-- forward_proxy_settings — Singleton-Row für globale Squid-Einstellungen.
+-- listen_addresses: Komma-separierte IPs auf denen Squid lauscht.
+-- Leer = alle Interfaces (http_port 3128). Typisch: LAN/VLAN-Gateway-IPs.
+CREATE TABLE IF NOT EXISTS forward_proxy_settings (
+    id               INTEGER PRIMARY KEY DEFAULT 1,
+    listen_addresses TEXT NOT NULL DEFAULT '',
+    listen_port      INTEGER NOT NULL DEFAULT 3128,
+    created_at       TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at       TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    CONSTRAINT forward_proxy_settings_singleton CHECK (id = 1)
+);
+
+INSERT INTO forward_proxy_settings (id) VALUES (1) ON CONFLICT DO NOTHING;
+
+-- +goose StatementEnd
+
+-- +goose Down
+-- +goose StatementBegin
+
+DROP TABLE IF EXISTS forward_proxy_settings;
+
+-- +goose StatementEnd