fix(pipeline): harden upstream resilience and production shutdown

DoH через DoWithRetry; CDN preview через UpstreamHTTPDo; частичный fail CDN (EVOBGP_CDN_PARTIAL_OK); безопасный доступ к Job.Meta; drain jobs при SIGTERM; ValidateProductionEnforce при EVOBGP_PRODUCTION=1.

Co-authored-by: Cursor <[email protected]>

internal/jobs/postgres_worker.go

@@ -93,9 +93,9 @@ func (w *Worker) runPostgresMaint(j *Job, kind string) {
 		j.Fail("postgresql not configured")
 		return
 	}
-	table, _ := j.Meta["table"].(string)
-	dryRun, _ := j.Meta["dry_run"].(bool)
-	actor, _ := j.Meta["actor_prefix"].(string)
+	table := j.metaString("table")
+	dryRun := j.metaBool("dry_run")
+	actor := j.metaString("actor_prefix")
 	ctx, cancel := j.workContext()
 	defer cancel()
 	auditID, _ := pgmonitor.InsertMaintenanceAudit(ctx, w.PgPool, j.TenantID, actor, kind, table, dryRun)