feat(push): log push provider config status on startup

Print ✓/✗ for each platform (FCM/HMS/MI/OPPO/VIVO) so missing credentials
are immediately visible in container logs.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/services/notification-service/src/application/services/offline-push.service.ts

@@ -1,4 +1,4 @@
-import { Injectable, Logger } from '@nestjs/common';
+import { Injectable, Logger, OnModuleInit } from '@nestjs/common';
 import { DevicePushTokenRepository } from '../../infrastructure/repositories/device-push-token.repository';
 import { DevicePushToken } from '../../domain/entities/device-push-token.entity';
 import { PushProvider, PushMessage } from './push-providers/push-provider.interface';
@@ -33,7 +33,7 @@ export interface NotificationForPush {
  * Invalid tokens returned by providers are automatically deleted from DB.
  */
 @Injectable()
-export class OfflinePushService {
+export class OfflinePushService implements OnModuleInit {
   private readonly logger = new Logger(OfflinePushService.name);
   private readonly providers: Map<string, PushProvider>;
 
@@ -54,6 +54,16 @@ export class OfflinePushService {
     ]);
   }
 
+  onModuleInit(): void {
+    for (const [platform, provider] of this.providers) {
+      if (provider.isConfigured()) {
+        this.logger.log(`[Push] ${platform} ✓ configured`);
+      } else {
+        this.logger.warn(`[Push] ${platform} ✗ NOT configured (credentials missing)`);
+      }
+    }
+  }
+
   sendForNotification(notification: NotificationForPush): void {
     this._send(notification).catch((err) => {
       this.logger.error(`Offline push failed for ${notification.id}: ${err.message}`);