Add full-stack Hello World app with CI/CD

- Go backend with PostgreSQL connection
- Next.js frontend with TypeScript
- Docker Compose for local development
- Woodpecker CI pipeline for build and push
- Kubernetes manifests with Kustomize
- ArgoCD application for GitOps deployment

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

manifests/postgres-deployment.yaml

@@ -0,0 +1,56 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: postgres
+  namespace: hell-world
+  labels:
+    app: postgres
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: postgres
+  template:
+    metadata:
+      labels:
+        app: postgres
+    spec:
+      containers:
+        - name: postgres
+          image: postgres:16-alpine
+          ports:
+            - containerPort: 5432
+              name: postgres
+          envFrom:
+            - secretRef:
+                name: postgres-secret
+          resources:
+            requests:
+              memory: "128Mi"
+              cpu: "100m"
+            limits:
+              memory: "256Mi"
+              cpu: "200m"
+          volumeMounts:
+            - name: postgres-data
+              mountPath: /var/lib/postgresql/data
+          livenessProbe:
+            exec:
+              command:
+                - pg_isready
+                - -U
+                - postgres
+            initialDelaySeconds: 30
+            periodSeconds: 10
+          readinessProbe:
+            exec:
+              command:
+                - pg_isready
+                - -U
+                - postgres
+            initialDelaySeconds: 5
+            periodSeconds: 5
+      volumes:
+        - name: postgres-data
+          persistentVolumeClaim:
+            claimName: postgres-pvc