refactor(ui): inject AuthRepository instead of FirebaseAuth.getInstance()

Five ViewModels reached into the FirebaseAuth.getInstance() static singleton for
the current user id; switch them to the injected AuthRepository.currentUserId
(BucketList, QuestionThread, DateBuilder, MessagesInbox, Conversation). Removes
the Firebase-in-presentation-layer coupling and makes them testable. No behavior
change; compiles + unit suite green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/src/main/java/app/closer/ui/dates/BucketListViewModel.kt

@@ -4,9 +4,9 @@ import android.util.Log
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import app.closer.domain.model.BucketListItem
+import app.closer.domain.repository.AuthRepository
 import app.closer.domain.repository.BucketListRepository
 import app.closer.domain.repository.CoupleRepository
-import com.google.firebase.auth.FirebaseAuth
 import dagger.hilt.android.lifecycle.HiltViewModel
 import javax.inject.Inject
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -18,7 +18,8 @@ import kotlinx.coroutines.launch
 @HiltViewModel
 class BucketListViewModel @Inject constructor(
     private val repository: BucketListRepository,
-    private val coupleRepository: CoupleRepository
+    private val coupleRepository: CoupleRepository,
+    private val authRepository: AuthRepository
 ) : ViewModel() {
 
     private val _uiState = MutableStateFlow(BucketListUiState())
@@ -33,7 +34,7 @@ class BucketListViewModel @Inject constructor(
 
     private fun resolveCouple() {
         viewModelScope.launch {
-            val uid = FirebaseAuth.getInstance().currentUser?.uid ?: return@launch
+            val uid = authRepository.currentUserId ?: return@launch
             runCatching { coupleRepository.getCoupleForUser(uid) }
                 .getOrNull()
                 ?.let { setCoupleId(it.id) }
@@ -69,7 +70,7 @@ class BucketListViewModel @Inject constructor(
             title = title.take(MAX_TITLE_LENGTH),
             description = description.take(MAX_DESCRIPTION_LENGTH),
             category = category,
-            addedBy = FirebaseAuth.getInstance().currentUser?.uid ?: "",
+            addedBy = authRepository.currentUserId ?: "",
             addedAt = System.currentTimeMillis()
         )
 
@@ -98,7 +99,7 @@ class BucketListViewModel @Inject constructor(
                         )
                     }
                 } else {
-                    repository.completeItem(coupleId, itemId, FirebaseAuth.getInstance().currentUser?.uid ?: "")
+                    repository.completeItem(coupleId, itemId, authRepository.currentUserId ?: "")
                     _uiState.update {
                         it.copy(
                             items = it.items.map {

app/src/main/java/app/closer/ui/dates/DateBuilderViewModel.kt

@@ -5,9 +5,9 @@ import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import app.closer.domain.model.DatePlan
 import app.closer.domain.model.DatePlanStatus
+import app.closer.domain.repository.AuthRepository
 import app.closer.domain.repository.CoupleRepository
 import app.closer.domain.repository.DatePlanRepository
-import com.google.firebase.auth.FirebaseAuth
 import dagger.hilt.android.lifecycle.HiltViewModel
 import javax.inject.Inject
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -19,7 +19,8 @@ import kotlinx.coroutines.launch
 @HiltViewModel
 class DateBuilderViewModel @Inject constructor(
     private val repository: DatePlanRepository,
-    private val coupleRepository: CoupleRepository
+    private val coupleRepository: CoupleRepository,
+    private val authRepository: AuthRepository
 ) : ViewModel() {
 
     private val _uiState = MutableStateFlow(DateBuilderUiState())
@@ -50,7 +51,7 @@ class DateBuilderViewModel @Inject constructor(
             // N-002: create a real PLANNED date_plan (surfaced on Home as the upcoming date) and resolve
             // the couple ourselves. Previously this wrote a date_plan_preference keyed off a dateIdeaId
             // that no entry ever set + an empty coupleId, so "Create Plan" silently saved nothing.
-            val uid = FirebaseAuth.getInstance().currentUser?.uid
+            val uid = authRepository.currentUserId
             val couple = uid?.let { runCatching { coupleRepository.getCoupleForUser(it) }.getOrNull() }
             if (couple == null) {
                 _uiState.update {

app/src/main/java/app/closer/ui/messages/ConversationViewModel.kt

@@ -8,12 +8,12 @@ import app.closer.core.billing.CouplePremiumChecker
 import app.closer.data.local.QuestionDao
 import app.closer.data.local.mapper.toQuestion
 import app.closer.domain.model.QuestionMessage
+import app.closer.domain.repository.AuthRepository
 import app.closer.domain.repository.ConversationRepository
 import app.closer.domain.repository.CoupleRepository
 import app.closer.domain.repository.UserRepository
 import app.closer.notifications.ActiveThreadMonitor
 import app.closer.ui.components.TextInputLimits
-import com.google.firebase.auth.FirebaseAuth
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.Job
@@ -60,12 +60,13 @@ class ConversationViewModel @Inject constructor(
     private val activeThreadMonitor: ActiveThreadMonitor,
     private val couplePremiumChecker: CouplePremiumChecker,
     private val analyticsTracker: AnalyticsTracker,
+    authRepository: AuthRepository,
     savedStateHandle: SavedStateHandle
 ) : ViewModel() {
 
     private val coupleId: String = savedStateHandle["coupleId"] ?: ""
     private val conversationId: String = savedStateHandle["conversationId"] ?: ""
-    val currentUserId: String = FirebaseAuth.getInstance().currentUser?.uid ?: ""
+    val currentUserId: String = authRepository.currentUserId ?: ""
 
     private val _uiState = MutableStateFlow(ConversationUiState())
     val uiState: StateFlow<ConversationUiState> = _uiState.asStateFlow()

app/src/main/java/app/closer/ui/messages/MessagesInboxViewModel.kt

@@ -5,10 +5,10 @@ import androidx.lifecycle.viewModelScope
 import app.closer.data.local.QuestionDao
 import app.closer.data.local.mapper.toQuestion
 import app.closer.domain.model.Conversation
+import app.closer.domain.repository.AuthRepository
 import app.closer.domain.repository.ConversationRepository
 import app.closer.domain.repository.CoupleRepository
 import app.closer.domain.repository.UserRepository
-import com.google.firebase.auth.FirebaseAuth
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
@@ -30,10 +30,11 @@ class MessagesInboxViewModel @Inject constructor(
     private val repository: ConversationRepository,
     private val coupleRepository: CoupleRepository,
     private val userRepository: UserRepository,
-    private val questionDao: QuestionDao
+    private val questionDao: QuestionDao,
+    authRepository: AuthRepository
 ) : ViewModel() {
 
-    private val currentUserId: String = FirebaseAuth.getInstance().currentUser?.uid ?: ""
+    private val currentUserId: String = authRepository.currentUserId ?: ""
 
     private val _uiState = MutableStateFlow(MessagesInboxUiState())
     val uiState: StateFlow<MessagesInboxUiState> = _uiState.asStateFlow()

app/src/main/java/app/closer/ui/questions/QuestionThreadViewModel.kt

@@ -13,7 +13,6 @@ import app.closer.domain.model.QuestionMessage
 import app.closer.domain.model.QuestionReaction
 import app.closer.domain.repository.QuestionThreadRepository
 import app.closer.ui.components.TextInputLimits
-import com.google.firebase.auth.FirebaseAuth
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
@@ -54,12 +53,13 @@ class QuestionThreadViewModel @Inject constructor(
     private val localAnswerRepository: app.closer.domain.repository.LocalAnswerRepository,
     private val userRepository: app.closer.domain.repository.UserRepository,
     private val coupleRepository: app.closer.domain.repository.CoupleRepository,
+    authRepository: app.closer.domain.repository.AuthRepository,
     savedStateHandle: SavedStateHandle
 ) : ViewModel() {
 
     private val coupleId: String = savedStateHandle["coupleId"] ?: ""
     private val questionId: String = savedStateHandle["questionId"] ?: ""
-    val currentUserId: String = FirebaseAuth.getInstance().currentUser?.uid ?: ""
+    val currentUserId: String = authRepository.currentUserId ?: ""
 
     // Released-once guard for our thread reveal key.
     private var threadKeyReleased = false