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/webinar-checker.yaml

@@ -47,6 +47,10 @@ spec:
         - name: webinar-checker
           image: gcr.forust.xyz/forust/webinar-checker:latest
           imagePullPolicy: Always
+          ports:
+            - name: metrics
+              containerPort: 8000
+              protocol: TCP
           envFrom:
             - secretRef:
                 name: edu-master-secrets