fix(k8s): update app labels to use recommended format

Refactor Kubernetes deployment and service labels to follow 
the recommended label format. Change all occurrences of 
"app: lingonpaj-site" to "app.kubernetes.io/name: lingonpaj-site" 
for improved consistency and compliance with Kubernetes best 
practices.

k8s/deploy.yaml

@@ -3,7 +3,7 @@ kind: Deployment
 metadata:
   name: lingonpaj-site
   labels:
-    app: lingonpaj-site
+    app.kubernetes.io/name: lingonpaj-site
   annotations:
     kubernetes.io/change-cause: "${TIMESTAMP} Deployed commit id: ${COMMIT}"
 spec:
@@ -16,11 +16,11 @@ spec:
   minReadySeconds: 30
   selector:
     matchLabels:
-      app: lingonpaj-site
+      app.kubernetes.io/name: lingonpaj-site
   template:
     metadata:
       labels:
-        app: lingonpaj-site
+        app.kubernetes.io/name: lingonpaj-site
     spec:
       affinity:
         podAntiAffinity:
@@ -29,7 +29,7 @@ spec:
             podAffinityTerm:
               labelSelector:
                 matchExpressions:
-                - key: "app"
+                - key: "app.kubernetes.io/name"
                   operator: In
                   values:
                   - lingonpaj-site
@@ -63,11 +63,11 @@ kind: Service
 metadata:
   name: lingonpaj-site
   labels:
-    app: lingonpaj-site
+    app.kubernetes.io/name: lingonpaj-site
 spec:
   type: NodePort
   selector:
-    app: lingonpaj-site
+    app.kubernetes.io/name: lingonpaj-site
   ports:
   - port: 80
     targetPort: 80