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.

gitea/k8s/gitea.yaml

@@ -31,7 +31,7 @@ spec:
     spec:
       containers:
         - name: gitea
-          image: docker.gitea.com/gitea:1.27.3
+          image: gitea/gitea:1.27.3
           envFrom:
             - configMapRef:
                 name: gitea-config