feat(matrix): add tuwunel Matrix homeserver deployment manifests

Kubernetes manifests for tuwunel — a Rust Matrix homeserver using RocksDB
for storage. Includes deployment, service, PVC, ConfigMap (tuwunel.toml),
Hydra OAuth2Client for SSO, and Vault secrets for credentials injection.

Key design decisions:
- enableServiceLinks: false to prevent K8s TUWUNEL_* env var conflicts
- strategy: Recreate for RocksDB exclusive lock (no rolling updates)
- Identity provider configured entirely via env vars (client_id/secret
  from hydra-maester Secret, not hardcoded)
- OpenSearch model_id injected via ConfigMap from CLI post-apply hook
- SSO-only auth (login_with_password=false, single_sso=true)
- OpenSearch hybrid neural+BM25 search (768-dim, all-mpnet-base-v2)

base/matrix/tuwunel-deployment.yaml

@@ -0,0 +1,91 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: tuwunel
+  namespace: matrix
+spec:
+  replicas: 1
+  strategy:
+    type: Recreate
+  selector:
+    matchLabels:
+      app: tuwunel
+  template:
+    metadata:
+      labels:
+        app: tuwunel
+    spec:
+      enableServiceLinks: false
+      containers:
+        - name: tuwunel
+          image: tuwunel
+          ports:
+            - name: http
+              containerPort: 6167
+              protocol: TCP
+          env:
+            - name: TUWUNEL_CONFIG
+              value: /etc/tuwunel/tuwunel.toml
+            - name: TUWUNEL_TURN_SECRET
+              valueFrom:
+                secretKeyRef:
+                  name: tuwunel-secrets
+                  key: TUWUNEL_TURN_SECRET
+            - name: TUWUNEL_REGISTRATION_TOKEN
+              valueFrom:
+                secretKeyRef:
+                  name: tuwunel-secrets
+                  key: TUWUNEL_REGISTRATION_TOKEN
+            - name: TUWUNEL_SEARCH_OPENSEARCH_MODEL_ID
+              valueFrom:
+                configMapKeyRef:
+                  name: opensearch-ml-config
+                  key: model_id
+                  optional: true
+            - name: TUWUNEL_IDENTITY_PROVIDER__0__BRAND
+              value: "Sunbeam"
+            - name: TUWUNEL_IDENTITY_PROVIDER__0__ISSUER_URL
+              value: "https://auth.DOMAIN_SUFFIX/"
+            - name: TUWUNEL_IDENTITY_PROVIDER__0__DEFAULT
+              value: "true"
+            - name: TUWUNEL_IDENTITY_PROVIDER__0__CLIENT_ID
+              valueFrom:
+                secretKeyRef:
+                  name: oidc-tuwunel
+                  key: CLIENT_ID
+            - name: TUWUNEL_IDENTITY_PROVIDER__0__CLIENT_SECRET
+              valueFrom:
+                secretKeyRef:
+                  name: oidc-tuwunel
+                  key: CLIENT_SECRET
+          volumeMounts:
+            - name: tuwunel-data
+              mountPath: /data
+            - name: tuwunel-config
+              mountPath: /etc/tuwunel/tuwunel.toml
+              subPath: tuwunel.toml
+          livenessProbe:
+            httpGet:
+              path: /_matrix/client/versions
+              port: 6167
+            initialDelaySeconds: 15
+            periodSeconds: 30
+          readinessProbe:
+            httpGet:
+              path: /_matrix/client/versions
+              port: 6167
+            initialDelaySeconds: 5
+            periodSeconds: 10
+          resources:
+            limits:
+              memory: 1Gi
+            requests:
+              memory: 512Mi
+              cpu: 250m
+      volumes:
+        - name: tuwunel-data
+          persistentVolumeClaim:
+            claimName: tuwunel-data
+        - name: tuwunel-config
+          configMap:
+            name: tuwunel-config