feat(cluster): PG Logical Replication + VIP/Keepalived + config_hash sync (v1.2.1–1.2.2)

- PG Logical Replication: edgeguard_shared PUBLICATION auf Primary,
  edgeguard_sub SUBSCRIPTION auf Secondary. Nur geteilte Config-Tabellen
  werden repliziert; node-eigene Daten (network_interfaces, ip_addresses,
  static_routes, cluster_settings, dns_settings, ntp_settings) bleiben
  lokal — OPNsense-Muster.
- cluster-init-replication: Erstellt PUBLICATION, Rolle + pg_hba-Einträge
  (logical + replication), WAL-Level auf logical.
- cluster-setup-standby: Erstellt SUBSCRIPTION (copy_data=true), pollt
  pg_subscription_rel bis alle Tabellen sync = 'r', rendert dann Configs.
- promote: manueller Failover via pg_promote() + touch recovery.signal.
- VIP/Keepalived: cluster_settings-Tabelle (vip_address, vip_interface,
  vrrp_router_id), /cluster/vip-settings API, Keepalived-Config-Generator
  mit VRRP + check_script + notify-Skripten in /usr/lib/edgeguard/scripts/.
- config_hash sync: Secondary pusht alle 5 Min seinen Hash via mTLS an
  Primary (PushSelfToPrimary). Heartbeat schreibt nur LOCAL, daher ohne
  aktiven Push wäre Primary-Sicht des Secondary-Hash stale gewesen.
- runSecondaryConfigRender: Goroutine auf Secondary rendert HAProxy+nftables
  neu wenn config_hash sich ändert (Logical-Replication-Nachzügler).
- confighash: node-spezifische Tabellen aus hashSpec entfernt.
- postinst: Keepalived-Skripte installieren, sudoers für keepalived.

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

internal/database/migrations/0029_cluster_vip.sql

@@ -0,0 +1,36 @@
+-- +goose Up
+-- +goose StatementBegin
+
+-- pg_role: Rolle dieser Node in der PG-Replikation.
+-- "standalone" = kein Streaming-Replication-Setup
+-- "primary"    = WAL-Sender, repliziert an Standby(s)
+-- "standby"    = Hot-Standby, liest WAL vom Primary
+ALTER TABLE ha_nodes ADD COLUMN IF NOT EXISTS pg_role TEXT NOT NULL DEFAULT 'standalone';
+
+-- cluster_settings: VIP + VRRP-Konfiguration (Singleton, id=1).
+-- vip_address   = die virtuelle IP-Adresse (z.B. "89.163.205.10")
+-- vip_interface = Netzwerk-Interface (z.B. "eth0")
+-- vip_auth_pass = VRRP-Authentication-Passwort (max. 8 Zeichen, Keepalived-Limit)
+-- vrrp_router_id = VRRP Virtual Router ID (1–255, muss im Subnetz eindeutig sein)
+CREATE TABLE IF NOT EXISTS cluster_settings (
+    id              INTEGER PRIMARY KEY DEFAULT 1,
+    vip_address     TEXT,
+    vip_interface   TEXT,
+    vip_auth_pass   TEXT,
+    vrrp_router_id  INTEGER NOT NULL DEFAULT 51,
+    created_at      TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at      TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    CONSTRAINT cluster_settings_singleton CHECK (id = 1)
+);
+
+INSERT INTO cluster_settings (id) VALUES (1) ON CONFLICT DO NOTHING;
+
+-- +goose StatementEnd
+
+-- +goose Down
+-- +goose StatementBegin
+
+DROP TABLE IF EXISTS cluster_settings;
+ALTER TABLE ha_nodes DROP COLUMN IF EXISTS pg_role;
+
+-- +goose StatementEnd