feat: ingest burst hardening — defer lifecycle/auth, workers, nginx (v0.5.5)

Defer notify_lifecycle and notify_auth_login after commit; SAC_UVICORN_WORKERS via sac-api-start.sh; nginx /api/v1/events timeout; mass-update confirm in Hosts UI.

frontend/src/views/HostsView.vue

@@ -138,6 +138,7 @@ import {
   remoteActionTitleForHost,
 } from "../utils/hostAgentUpgrade";
 import {
+  hostRemoteActionLogs,
   isHostRemoteActionActive,
   pollHostRemoteAction,
   runHostRemoteAction,
@@ -244,6 +245,37 @@ function isVersionOutdated(h: HostSummary): boolean {
   return isAgentVersionOutdated(h.product_version, reference);
 }
 
+function countOutdatedUpgradeableHosts(): number {
+  return (data.value?.items ?? []).filter(
+    (h) => isGitAgentUpgradeAvailable(h, data.value) && isVersionOutdated(h),
+  ).length;
+}
+
+function countActiveRemoteUpgrades(): number {
+  return hostRemoteActionLogs.filter((e) => e.loading).length;
+}
+
+function confirmMassUpgradeIfNeeded(hostname: string): boolean {
+  const active = countActiveRemoteUpgrades();
+  const outdated = countOutdatedUpgradeableHosts();
+  if (active >= 2) {
+    return window.confirm(
+      `Сейчас обновляется ${active} хост(ов). Рекомендуется пачками по 2–3. Продолжить обновление «${hostname}»?`,
+    );
+  }
+  if (outdated > 3 && active >= 1) {
+    return window.confirm(
+      `Устарело агентов на странице: ${outdated}, уже идёт обновление. Продолжить «${hostname}»?`,
+    );
+  }
+  if (outdated > 3) {
+    return window.confirm(
+      `Устарело агентов на странице: ${outdated}. Рекомендуется обновлять пачками по 2–3, не все сразу. Продолжить «${hostname}»?`,
+    );
+  }
+  return true;
+}
+
 async function startAgentUpgrade(h: HostSummary) {
   if (!isGitAgentUpgradeAvailable(h, data.value)) {
     return;
@@ -252,6 +284,9 @@ async function startAgentUpgrade(h: HostSummary) {
     showHostRemoteActionLog(h.id);
     return;
   }
+  if (!confirmMassUpgradeIfNeeded(h.hostname)) {
+    return;
+  }
   const kind = remoteActionKindForHost(h);
   if (!kind) return;
   void runHostRemoteAction(h.id, remoteActionTitleForHost(h), kind);