feat(system-time): implement default NTP server configuration

- Added functionality to default to 'pool.ntp.org' when no NTP servers are configured in the SystemTimeService.
- Updated the service logic to handle scenarios where NTP servers are not explicitly set, ensuring a fallback to the default server.
- Introduced a new test case to verify the default NTP server behavior, enhancing test coverage for system time configuration.

These changes improve the reliability of time synchronization settings in the system.

api/src/unraid-api/graph/resolvers/system-time/system-time.service.spec.ts

@@ -94,6 +94,39 @@ describe('SystemTimeService', () => {
         });
     });
 
+    it('defaults to pool.ntp.org when no NTP servers are configured', async () => {
+        vi.mocked(configService.get).mockImplementation((key: string, defaultValue?: any) => {
+            if (key === 'store.emhttp.var') {
+                return {
+                    timeZone: 'UTC',
+                    useNtp: true,
+                    ntpServer1: '',
+                    ntpServer2: '',
+                    ntpServer3: '',
+                    ntpServer4: '',
+                };
+            }
+            if (key === 'store.paths.webGuiBase') {
+                return '/usr/local/emhttp/webGui';
+            }
+            return defaultValue;
+        });
+
+        await service.updateSystemTime({ timeZone: 'America/New_York' });
+
+        expect(emcmd).toHaveBeenCalledTimes(1);
+        const [commands] = vi.mocked(emcmd).mock.calls[0];
+        expect(commands).toEqual({
+            setDateTime: 'apply',
+            timeZone: 'America/New_York',
+            USE_NTP: 'yes',
+            NTP_SERVER1: 'pool.ntp.org',
+            NTP_SERVER2: '',
+            NTP_SERVER3: '',
+            NTP_SERVER4: '',
+        });
+    });
+
     it('updates time settings, disables NTP, and triggers timezone reset', async () => {
         const oldState = {
             timeZone: 'UTC',

api/src/unraid-api/graph/resolvers/system-time/system-time.service.ts

@@ -13,6 +13,7 @@ import {
 } from '@app/unraid-api/graph/resolvers/system-time/system-time.model.js';
 
 const MAX_NTP_SERVERS = 4;
+const DEFAULT_NTP_SERVER = 'pool.ntp.org';
 
 @Injectable()
 export class SystemTimeService {
@@ -42,14 +43,28 @@ export class SystemTimeService {
         this.validateTimeZone(desiredTimeZone);
 
         const hasCurrentUseNtp = typeof current.useNtp !== 'undefined';
-        const desiredUseNtp = input.useNtp ?? (hasCurrentUseNtp ? Boolean(current.useNtp) : undefined);
         const hasCurrentNtpServers = this.hasNtpServerState(current);
-        const desiredServers =
-            input.ntpServers !== undefined
-                ? this.normalizeNtpServers(input.ntpServers, current)
-                : hasCurrentNtpServers
-                  ? this.normalizeNtpServers(undefined, current)
-                  : null;
+        const currentServers = hasCurrentNtpServers
+            ? this.normalizeNtpServers(undefined, current)
+            : null;
+        const hasConfiguredServers = currentServers
+            ? currentServers.some((server) => server.length > 0)
+            : false;
+        const allowDefaultNtp = input.useNtp !== false;
+
+        let desiredUseNtp = input.useNtp ?? (hasCurrentUseNtp ? Boolean(current.useNtp) : undefined);
+        let desiredServers: string[] | null = null;
+
+        if (input.ntpServers !== undefined) {
+            desiredServers = this.normalizeNtpServers(input.ntpServers, current);
+        } else if (hasCurrentNtpServers) {
+            if (!hasConfiguredServers && allowDefaultNtp) {
+                desiredServers = this.normalizeNtpServers([DEFAULT_NTP_SERVER], current);
+                desiredUseNtp = true;
+            } else {
+                desiredServers = currentServers;
+            }
+        }
 
         const commands: Record<string, string> = {
             setDateTime: 'apply',