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/aggregator/aggregator.go

@@ -229,6 +229,43 @@ func (a *Aggregator) PostPeer(ctx context.Context, p models.HANode, path string)
 	return res
 }
 
+// PostPeerWithBody sendet einen POST-Request mit JSON-Body an einen Peer.
+// Wird für VIP-Schwenk-Tests genutzt (/agent/cluster/vip-cmd).
+func (a *Aggregator) PostPeerWithBody(ctx context.Context, p models.HANode, path string, body []byte) PeerResult {
+	start := time.Now()
+	res := PeerResult{NodeID: p.ID, FQDN: p.FQDN}
+	target, err := agentURL(p.APIURL, a.AgentPort, path)
+	if err != nil {
+		res.Err = "bad api_url: " + err.Error()
+		return res
+	}
+	reqCtx, cancel := context.WithTimeout(ctx, 15*time.Second)
+	defer cancel()
+	req, err := http.NewRequestWithContext(reqCtx, http.MethodPost, target, strings.NewReader(string(body)))
+	if err != nil {
+		res.Err = err.Error()
+		return res
+	}
+	req.Header.Set("Content-Type", "application/json")
+	resp, err := a.HTTPClient.Do(req)
+	if err != nil {
+		res.Err = err.Error()
+		res.Duration = time.Since(start).Milliseconds()
+		return res
+	}
+	defer resp.Body.Close()
+	respBody, _ := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
+	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusAccepted && resp.StatusCode != http.StatusNoContent {
+		res.Err = fmt.Sprintf("HTTP %d: %s", resp.StatusCode, strings.TrimSpace(string(respBody)))
+		res.Duration = time.Since(start).Milliseconds()
+		return res
+	}
+	res.OK = true
+	res.Data = respBody
+	res.Duration = time.Since(start).Milliseconds()
+	return res
+}
+
 // Compile-time check dass cluster importiert wird (für Drift-Detection
 // vom hashSpec — die Aggregator-Resultate werden parallel im Drift-
 // Banner mitverarbeitet). Nicht runtime-essentiell, aber dokumentiert