feat(version-check): add HERMES_WEB_UI_DISABLE_UPDATE_CHECK env var (#1105)

Adds an opt-in environment variable to suppress the npm-registry update
check. When set, three things change:

1. checkLatestVersion() returns immediately (no outbound fetch)
2. startVersionCheck() does not arm the 30-minute interval
3. /api/health returns webui_latest='' and webui_update_available=false

Use case: hermes-web-ui is bundled inside a packaged distribution like
a desktop app where the user cannot `npm install -g hermes-web-ui@latest`
to apply an upgrade. The 'update available' prompt is then misleading
(the user would have to wait for the wrapper app to ship a new release),
and the recurring HTTPS call to the npm registry is unnecessary noise.

Set HERMES_WEB_UI_DISABLE_UPDATE_CHECK=true | 1 | on | yes to disable.
The default behavior is unchanged.

Discussed in #1091 — proposed by @EKKOLearnAI.

packages/server/src/controllers/health.ts

@@ -45,7 +45,23 @@ const LOCAL_VERSION = typeof __APP_VERSION__ !== 'undefined'
 
 let cachedLatestVersion = ''
 
+/**
+ * Whether the periodic npm-registry version check is disabled.
+ *
+ * Useful when hermes-web-ui is bundled inside a packaged distribution
+ * (e.g. a desktop app) where the user can't `npm install -g hermes-web-ui@latest`
+ * to upgrade — the "update available" prompt would be misleading and
+ * the periodic outbound HTTP request to the npm registry is unnecessary.
+ *
+ * Set HERMES_WEB_UI_DISABLE_UPDATE_CHECK=true (or 1, on, yes) to disable.
+ */
+function isUpdateCheckDisabled(): boolean {
+  const raw = (process.env.HERMES_WEB_UI_DISABLE_UPDATE_CHECK || '').trim().toLowerCase()
+  return raw === 'true' || raw === '1' || raw === 'on' || raw === 'yes'
+}
+
 export async function checkLatestVersion(): Promise<void> {
+  if (isUpdateCheckDisabled()) return
   try {
     const packageName = PACKAGE_INFO?.name || 'hermes-web-ui'
     const registryName = encodeURIComponent(packageName)
@@ -61,6 +77,7 @@ export async function checkLatestVersion(): Promise<void> {
 }
 
 export function startVersionCheck(): void {
+  if (isUpdateCheckDisabled()) return
   setTimeout(checkLatestVersion, 5000)
   setInterval(checkLatestVersion, 30 * 60 * 1000)
 }
@@ -74,8 +91,10 @@ export async function healthCheck(ctx: any) {
     version: hermesVersion,
     gateway: 'running',
     webui_version: LOCAL_VERSION,
-    webui_latest: cachedLatestVersion,
+    webui_latest: isUpdateCheckDisabled() ? '' : cachedLatestVersion,
-    webui_update_available: Boolean(LOCAL_VERSION && cachedLatestVersion && cachedLatestVersion !== LOCAL_VERSION),
+    webui_update_available: isUpdateCheckDisabled()
+      ? false
+      : Boolean(LOCAL_VERSION && cachedLatestVersion && cachedLatestVersion !== LOCAL_VERSION),
     node_version: process.versions.node,
   }
 }