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.

edu_master/k8s/servicemonitor.yaml

@@ -0,0 +1,16 @@
+apiVersion: monitoring.coreos.com/v1
+kind: ServiceMonitor
+metadata:
+  name: webinar-checker
+  namespace: edu-master
+  labels:
+    release: prometheus-stack
+spec:
+  selector:
+    matchLabels:
+      app: edu-master-webinar-checker
+  endpoints:
+    - port: metrics
+      path: /metrics
+      interval: 30s
+      scrapeTimeout: 10s