authentik HA: fix Istio ambient mesh blocking VPS/witness streaming replication

CNPG's new externalClusters connectionParameters were configured correctly
but streaming replication was silently failing - pg_stat_wal_receiver on
the VPS replica showed 0 rows, logs repeated 'could not connect to the
primary server: ... server closed the connection unexpectedly' every few
minutes.

Root cause: the authentik namespace is enrolled in Istio ambient mesh with
the mesh-wide default PeerAuthentication set to STRICT, and its
AuthorizationPolicy only allows traffic from specific in-mesh namespaces.
Traffic arriving via the ha-authentik-postgres NodePort from the VPS/
witness has no mesh identity at all (they're not in this cluster), so
ztunnel accepted the TCP connection then reset it once no HBONE/mTLS
handshake and no matching ALLOW rule ever arrived - confirmed live via
openssl s_client -starttls postgres (TCP connects, 0 bytes back).

Same root cause and same fix as the existing hostNetwork/webhook precedent
(infrastructure/istio/manifests/mesh/peer-authentication-webhooks.yaml):
- New port-scoped PERMISSIVE PeerAuthentication for the pg-authentik pods'
  port 5432 only (not the whole namespace - Authentik's own in-mesh
  east-west traffic stays STRICT).
- New port-scoped ALLOW rule on the existing AuthorizationPolicy, so any
  source is allowed for port 5432 specifically, without touching the
  existing namespace-based rules.

Both layers were needed - PERMISSIVE mTLS alone isn't enough, the
AuthorizationPolicy independently denies anything not matching one of its
existing rules.

Verified live: restarted the VPS replica pod to force an immediate
reconnect attempt: FATAL connection-reset errors stopped, and it's now
progressing through WAL restore toward a live streaming connection.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

infrastructure/authentik/manifests/ha-postgres-peerauth.yaml

@@ -0,0 +1,40 @@
+# Multi-site active failover pilot (see
+# /home/scooby/.claude/plans/jiggly-snacking-iverson.md) - CNPG streaming
+# replication from the VPS was silently failing: `pg_stat_wal_receiver` on
+# the VPS replica showed 0 rows, and its logs showed a repeating
+# "could not connect to the primary server: ... server closed the
+# connection unexpectedly" every few minutes (confirmed live 2026-08-19).
+#
+# Root cause: the `authentik` namespace is enrolled in Istio's ambient mesh
+# (`istio.io/dataplane-mode: ambient`) and the mesh-wide default
+# PeerAuthentication (istio-system/default) is STRICT - ztunnel requires a
+# valid mesh (HBONE/SPIFHE) identity for ALL traffic to pods in this
+# namespace, including traffic arriving via the ha-authentik-postgres
+# NodePort from the VPS/witness (which have no mesh identity at all -
+# they're not in this cluster). ztunnel accepts the raw TCP connection then
+# resets it once it can't complete an mTLS handshake it never receives -
+# exactly matching the "server closed the connection unexpectedly"
+# symptom. Confirmed via `openssl s_client -starttls postgres`: TCP
+# connects, the postgres SSLRequest byte is sent, 0 bytes come back.
+#
+# Same root cause and same fix as the existing precedent for this exact
+# problem (infrastructure/istio/manifests/mesh/peer-authentication-webhooks.yaml
+# - CrowdSec's hostNetwork bouncer / the API server's webhook calls): allow
+# PERMISSIVE (mTLS or plaintext) inbound. Scoped here to just the CNPG
+# primary pod's port 5432 via portLevelMtls, rather than the whole
+# namespace like that precedent does - Authentik's own in-mesh east-west
+# traffic (server/worker -> everything else) should stay STRICT.
+apiVersion: security.istio.io/v1
+kind: PeerAuthentication
+metadata:
+  name: allow-ha-postgres-replication
+  namespace: authentik
+spec:
+  selector:
+    matchLabels:
+      cnpg.io/cluster: pg-authentik
+  mtls:
+    mode: STRICT
+  portLevelMtls:
+    "5432":
+      mode: PERMISSIVE