chore(deploy): rework k8s pipeline, monitoring and postgres 17

Deploy workflow uses git-tracked manifests, DISABLED flag and kustomize overlays; add webinar-checker metrics with ServiceMonitor and alerts; upgrade shared postgres to 17 with statuspage DB and probes/resources.

postgres/k8s/postgres.yaml

@@ -60,11 +60,23 @@ spec:
               command: ["pg_isready", "-U", "postgres", "-d", "postgres"]
             initialDelaySeconds: 10
             periodSeconds: 10
+          startupProbe:
+            exec:
+              command: ["pg_isready", "-U", "postgres", "-d", "postgres"]
+            failureThreshold: 30
+            periodSeconds: 10
           livenessProbe:
             exec:
               command: ["pg_isready", "-U", "postgres", "-d", "postgres"]
             initialDelaySeconds: 30
             periodSeconds: 20
+          resources:
+            requests:
+              memory: "512Mi"
+              cpu: "500m"
+            limits:
+              memory: "2Gi"
+              cpu: "2000m"
       volumes:
         - name: postgres-data
           persistentVolumeClaim: