fix: actively fetch FCM token on login if not cached

- LoginViewModel now calls Tasks.await(FirebaseMessaging.getInstance().token)
  to actively fetch the FCM token if not yet saved in prefs
- Previous code relied solely on onNewToken callback, which may not fire
  before the user logs in on a fresh install

android/app/src/main/java/com/devlab/app/ui/login/LoginViewModel.kt

@@ -8,10 +8,14 @@ import com.devlab.app.data.api.SessionManager
 import com.devlab.app.data.repository.AuthRepository
 import com.devlab.app.data.model.FcmRegisterRequest
 import com.devlab.app.util.PreferencesManager
+import com.google.android.gms.tasks.Tasks
+import com.google.firebase.messaging.FirebaseMessaging
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+import kotlinx.coroutines.Dispatchers
 
 data class LoginUiState(
     val username: String = "",
@@ -100,7 +104,17 @@ class LoginViewModel : ViewModel() {
 
     private suspend fun registerFcmToken() {
         try {
-            val fcmToken = prefs.getFcmToken()
+            var fcmToken = prefs.getFcmToken()
+            if (fcmToken.isBlank()) {
+                fcmToken = withContext(Dispatchers.IO) {
+                    try {
+                        Tasks.await(FirebaseMessaging.getInstance().token)
+                    } catch (_: Exception) { "" }
+                }
+                if (fcmToken.isNotBlank()) {
+                    prefs.saveFcmToken(fcmToken)
+                }
+            }
             if (fcmToken.isNotBlank()) {
                 val service = RetrofitClient.getApiService()
                 service.registerFcmToken(FcmRegisterRequest(fcmToken))