feat: add feature branch deployments with per-branch isolation

Enable deploying feature branches into isolated environments on the same
k3s cluster. Each branch gets its own namespace (cam-<slug>), PostgreSQL
schema, and OpenSearch index prefix for data isolation while sharing the
underlying infrastructure.

- Make OpenSearch index prefix and DB schema configurable via env vars
  (defaults preserve existing behavior)
- Restructure deploy/ into Kustomize base + overlays (main/feature)
- Extend CI to build Docker images for all branches, not just main
- Add deploy-feature job with namespace creation, secret copying,
  Traefik Ingress routing (<slug>-api/ui.cameleer.siegeln.net)
- Add cleanup-branch job to remove namespace, PG schema, OS indices
  on branch deletion
- Install required tools (git, jq, curl) in CI deploy containers

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

deploy/base/server.yaml

@@ -0,0 +1,124 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: cameleer3-server
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: cameleer3-server
+  template:
+    metadata:
+      labels:
+        app: cameleer3-server
+    spec:
+      imagePullSecrets:
+        - name: gitea-registry
+      containers:
+        - name: server
+          image: gitea.siegeln.net/cameleer/cameleer3-server:latest
+          ports:
+            - containerPort: 8081
+          env:
+            - name: SPRING_DATASOURCE_URL
+              value: "jdbc:postgresql://postgres.cameleer.svc.cluster.local:5432/cameleer3?currentSchema=$(CAMELEER_DB_SCHEMA)"
+            - name: CAMELEER_DB_SCHEMA
+              value: "public"
+            - name: SPRING_DATASOURCE_USERNAME
+              valueFrom:
+                secretKeyRef:
+                  name: postgres-credentials
+                  key: POSTGRES_USER
+            - name: SPRING_DATASOURCE_PASSWORD
+              valueFrom:
+                secretKeyRef:
+                  name: postgres-credentials
+                  key: POSTGRES_PASSWORD
+            - name: OPENSEARCH_URL
+              value: "http://opensearch.cameleer.svc.cluster.local:9200"
+            - name: CAMELEER_OPENSEARCH_INDEX_PREFIX
+              value: "executions-"
+            - name: CAMELEER_AUTH_TOKEN
+              valueFrom:
+                secretKeyRef:
+                  name: cameleer-auth
+                  key: CAMELEER_AUTH_TOKEN
+            - name: CAMELEER_UI_USER
+              valueFrom:
+                secretKeyRef:
+                  name: cameleer-auth
+                  key: CAMELEER_UI_USER
+                  optional: true
+            - name: CAMELEER_UI_PASSWORD
+              valueFrom:
+                secretKeyRef:
+                  name: cameleer-auth
+                  key: CAMELEER_UI_PASSWORD
+                  optional: true
+            - name: CAMELEER_UI_ORIGIN
+              value: "http://localhost:5173"
+            - name: CAMELEER_JWT_SECRET
+              valueFrom:
+                secretKeyRef:
+                  name: cameleer-auth
+                  key: CAMELEER_JWT_SECRET
+                  optional: true
+            - name: CAMELEER_OIDC_ENABLED
+              valueFrom:
+                secretKeyRef:
+                  name: cameleer-oidc
+                  key: CAMELEER_OIDC_ENABLED
+                  optional: true
+            - name: CAMELEER_OIDC_ISSUER
+              valueFrom:
+                secretKeyRef:
+                  name: cameleer-oidc
+                  key: CAMELEER_OIDC_ISSUER
+                  optional: true
+            - name: CAMELEER_OIDC_CLIENT_ID
+              valueFrom:
+                secretKeyRef:
+                  name: cameleer-oidc
+                  key: CAMELEER_OIDC_CLIENT_ID
+                  optional: true
+            - name: CAMELEER_OIDC_CLIENT_SECRET
+              valueFrom:
+                secretKeyRef:
+                  name: cameleer-oidc
+                  key: CAMELEER_OIDC_CLIENT_SECRET
+                  optional: true
+          resources:
+            requests:
+              memory: "256Mi"
+              cpu: "100m"
+            limits:
+              memory: "512Mi"
+              cpu: "500m"
+          livenessProbe:
+            httpGet:
+              path: /api/v1/health
+              port: 8081
+            initialDelaySeconds: 30
+            periodSeconds: 10
+            timeoutSeconds: 3
+            failureThreshold: 3
+          readinessProbe:
+            httpGet:
+              path: /api/v1/health
+              port: 8081
+            initialDelaySeconds: 10
+            periodSeconds: 5
+            timeoutSeconds: 3
+            failureThreshold: 3
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: cameleer3-server
+spec:
+  type: ClusterIP
+  selector:
+    app: cameleer3-server
+  ports:
+    - port: 8081
+      targetPort: 8081