deploy: replace ClickHouse with PostgreSQL/TimescaleDB + OpenSearch in K8s manifests

- Dockerfile: update default SPRING_DATASOURCE_URL to jdbc:postgresql, add OPENSEARCH_URL default env
- deploy/postgres.yaml: new TimescaleDB StatefulSet + headless Service (10Gi PVC, pg_isready probes)
- deploy/opensearch.yaml: new OpenSearch 2.19.0 StatefulSet + headless Service (10Gi PVC, single-node, security disabled)
- deploy/server.yaml: switch datasource env from clickhouse-credentials to postgres-credentials, add OPENSEARCH_URL

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

deploy/postgres.yaml

@@ -0,0 +1,91 @@
+apiVersion: apps/v1
+kind: StatefulSet
+metadata:
+  name: postgres
+  namespace: cameleer
+spec:
+  serviceName: postgres
+  replicas: 1
+  selector:
+    matchLabels:
+      app: postgres
+  template:
+    metadata:
+      labels:
+        app: postgres
+    spec:
+      containers:
+        - name: postgres
+          image: timescale/timescaledb:latest-pg16
+          ports:
+            - containerPort: 5432
+              name: postgres
+          env:
+            - name: POSTGRES_DB
+              value: cameleer3
+            - name: POSTGRES_USER
+              valueFrom:
+                secretKeyRef:
+                  name: postgres-credentials
+                  key: POSTGRES_USER
+            - name: POSTGRES_PASSWORD
+              valueFrom:
+                secretKeyRef:
+                  name: postgres-credentials
+                  key: POSTGRES_PASSWORD
+          volumeMounts:
+            - name: data
+              mountPath: /var/lib/postgresql/data
+          resources:
+            requests:
+              memory: "1Gi"
+              cpu: "200m"
+            limits:
+              memory: "4Gi"
+              cpu: "1000m"
+          livenessProbe:
+            exec:
+              command:
+                - pg_isready
+                - -U
+                - cameleer
+                - -d
+                - cameleer3
+            initialDelaySeconds: 15
+            periodSeconds: 10
+            timeoutSeconds: 3
+            failureThreshold: 3
+          readinessProbe:
+            exec:
+              command:
+                - pg_isready
+                - -U
+                - cameleer
+                - -d
+                - cameleer3
+            initialDelaySeconds: 5
+            periodSeconds: 5
+            timeoutSeconds: 3
+            failureThreshold: 3
+  volumeClaimTemplates:
+    - metadata:
+        name: data
+      spec:
+        accessModes: ["ReadWriteOnce"]
+        resources:
+          requests:
+            storage: 10Gi
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: postgres
+  namespace: cameleer
+spec:
+  clusterIP: None
+  selector:
+    app: postgres
+  ports:
+    - port: 5432
+      targetPort: 5432
+      name: postgres