fix(updates): avoid network stack traces offline

tests/frontend/managers/updateService.test.js

@@ -0,0 +1,45 @@
+import { describe, beforeEach, afterEach, expect, it, vi } from 'vitest';
+import { UpdateService } from '../../../static/js/managers/UpdateService.js';
+
+function createFetchResponse(payload) {
+    return {
+        json: vi.fn().mockResolvedValue(payload)
+    };
+}
+
+describe('UpdateService passive checks', () => {
+    let service;
+    let fetchMock;
+
+    beforeEach(() => {
+        fetchMock = vi.fn().mockResolvedValue(createFetchResponse({
+            success: true,
+            current_version: 'v1.0.0',
+            latest_version: 'v1.0.0',
+            git_info: { short_hash: 'abc123' }
+        }));
+        global.fetch = fetchMock;
+
+        service = new UpdateService();
+        service.updateNotificationsEnabled = false;
+        service.lastCheckTime = 0;
+        service.nightlyMode = false;
+    });
+
+    afterEach(() => {
+        delete global.fetch;
+    });
+
+    it('skips passive update checks when notifications are disabled', async () => {
+        await service.checkForUpdates();
+
+        expect(fetchMock).not.toHaveBeenCalled();
+    });
+
+    it('allows manual checks even when notifications are disabled', async () => {
+        await service.checkForUpdates({ force: true });
+
+        expect(fetchMock).toHaveBeenCalledTimes(1);
+        expect(fetchMock).toHaveBeenCalledWith('/api/lm/check-updates?nightly=false');
+    });
+});