feat(kanidm): deploy Kanidm 1.10.3 with 2-replica replication

## Summary

- Deploys Kanidm 1.10.3 (ghcr.io/kanidm/server:1.10.3) as a 2-replica
  StatefulSet with built-in replication enabled
- Domain: auth.unkin.net (primary WebAuthn origin); au.auth.unkin.net
  is an additional hostname for this au-syd1 instance
- TLS: cert-manager Certificate (vault-issuer) covering auth.unkin.net,
  au.auth.unkin.net, kanidm.k8s.syd1.au.unkin.net, and internal
  headless pod DNS names — Kanidm terminates TLS itself (passthrough)
- Gateway: TLS passthrough on port 443 via TLSRoute; HTTP on port 80
  redirects to HTTPS; external-dns creates kanidm.k8s.syd1.au.unkin.net
  (not used in server.toml; canonical origin is auth.unkin.net only)
- Replication: init container generates per-pod server.toml with the
  correct repl:// origin (kanidm-{N}.kanidm-headless.kanidm.svc);
  populate kanidm-repl-peers ConfigMap post-deployment after running
  `kanidmd show-replication-certificate` on each pod
- Storage: 10Gi cephrbd-fast-delete PVC per pod via volumeClaimTemplates
- Security: runAsUser/runAsGroup 1000, runAsNonRoot, no privilege
  escalation, allowPrivilegeEscalation=false
- ArgoCD: platform ApplicationSet and Project updated for kanidm namespace

## Requires

- PR benvin/kanidm-artifactapi (add ^kanidm/ to ghcr immutable patterns)
  to be merged first so artifactapi can cache ghcr.io/kanidm/server

## Post-deployment steps

1. Wait for both pods to reach Running state
2. Exchange replication certificates between pods:
   kubectl exec -n kanidm kanidm-0 -- kanidmd show-replication-certificate
   kubectl exec -n kanidm kanidm-1 -- kanidmd show-replication-certificate
3. Edit kanidm-repl-peers ConfigMap with both nodes' certs
   (see template in configmap.yaml comments)
4. kubectl rollout restart statefulset/kanidm -n kanidm

## Test plan

- [x] Sandbox tested in sandbox-kanidm: all 11 resources server dry-run OK
- [ ] After merge: ArgoCD syncs kanidm namespace
- [ ] Verify auth.unkin.net and au.auth.unkin.net reachable via Gateway
- [ ] Verify kanidm.k8s.syd1.au.unkin.net DNS record created by external-dns
- [ ] Complete replication cert exchange and verify replication active

apps/base/kanidm/statefulset.yaml

@@ -0,0 +1,117 @@
+---
+apiVersion: apps/v1
+kind: StatefulSet
+metadata:
+  name: kanidm
+  namespace: kanidm
+  labels:
+    app.kubernetes.io/name: kanidm
+    app.kubernetes.io/instance: kanidm
+spec:
+  serviceName: kanidm-headless
+  replicas: 2
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: kanidm
+      app.kubernetes.io/instance: kanidm
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: kanidm
+        app.kubernetes.io/instance: kanidm
+    spec:
+      serviceAccountName: kanidm
+      securityContext:
+        runAsUser: 1000
+        runAsGroup: 1000
+        runAsNonRoot: true
+        fsGroup: 1000
+      initContainers:
+        - name: config-init
+          image: ghcr.io/kanidm/server:1.10.3
+          command: ["/bin/sh", "-c"]
+          args:
+            - |
+              set -e
+              REPL_ORIGIN="repl://${POD_NAME}.kanidm-headless.kanidm.svc.cluster.local:8444"
+              sed "s|__REPL_ORIGIN__|${REPL_ORIGIN}|g" /config-template/server.toml > /config/server.toml
+              if [ -s /repl-peers/peers.toml ]; then
+                cat /repl-peers/peers.toml >> /config/server.toml
+              fi
+          env:
+            - name: POD_NAME
+              valueFrom:
+                fieldRef:
+                  fieldPath: metadata.name
+          volumeMounts:
+            - name: config-template
+              mountPath: /config-template
+            - name: config
+              mountPath: /config
+            - name: repl-peers
+              mountPath: /repl-peers
+          securityContext:
+            allowPrivilegeEscalation: false
+            readOnlyRootFilesystem: true
+      containers:
+        - name: kanidm
+          image: ghcr.io/kanidm/server:1.10.3
+          command: ["/sbin/kanidmd"]
+          args: ["server", "-c", "/config/server.toml"]
+          ports:
+            - name: https
+              containerPort: 8443
+              protocol: TCP
+            - name: replication
+              containerPort: 8444
+              protocol: TCP
+          volumeMounts:
+            - name: data
+              mountPath: /data
+            - name: config
+              mountPath: /config
+              readOnly: true
+            - name: tls
+              mountPath: /data/tls
+              readOnly: true
+          securityContext:
+            allowPrivilegeEscalation: false
+            readOnlyRootFilesystem: false
+          resources:
+            requests:
+              memory: 256Mi
+              cpu: 100m
+            limits:
+              memory: 1Gi
+              cpu: 500m
+          readinessProbe:
+            tcpSocket:
+              port: 8443
+            initialDelaySeconds: 15
+            periodSeconds: 10
+          livenessProbe:
+            tcpSocket:
+              port: 8443
+            initialDelaySeconds: 30
+            periodSeconds: 30
+      volumes:
+        - name: config-template
+          configMap:
+            name: kanidm-config
+        - name: config
+          emptyDir: {}
+        - name: repl-peers
+          configMap:
+            name: kanidm-repl-peers
+        - name: tls
+          secret:
+            secretName: kanidm-tls
+  volumeClaimTemplates:
+    - metadata:
+        name: data
+      spec:
+        accessModes: [ReadWriteOnce]
+        storageClassName: cephrbd-fast-delete
+        resources:
+          requests:
+            storage: 10Gi