fix: smart navigation waits for DataStore before routing

Use flow.first() instead of collectAsState(initial = null) to
determine start destination. The previous approach fired immediately
with the initial null value before DataStore loaded from disk, always
routing to Setup. Now the loading screen suspends until preferences
are actually read.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/src/main/java/no/naiv/implausibly/MainActivity.kt

@@ -8,7 +8,6 @@ import androidx.activity.enableEdgeToEdge
 import dagger.hilt.android.AndroidEntryPoint
 import no.naiv.implausibly.data.AppPreferences
 import no.naiv.implausibly.data.repository.InstanceRepository
-import no.naiv.implausibly.data.repository.SiteRepository
 import no.naiv.implausibly.ui.navigation.AppNavHost
 import no.naiv.implausibly.ui.theme.ImplausiblyTheme
 import javax.inject.Inject
@@ -18,7 +17,6 @@ class MainActivity : ComponentActivity() {
 
     @Inject lateinit var appPreferences: AppPreferences
     @Inject lateinit var instanceRepository: InstanceRepository
-    @Inject lateinit var siteRepository: SiteRepository
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -27,8 +25,7 @@ class MainActivity : ComponentActivity() {
             ImplausiblyTheme {
                 AppNavHost(
                     appPreferences = appPreferences,
-                    instanceRepository = instanceRepository,
+                    instanceRepository = instanceRepository
-                    siteRepository = siteRepository
                 )
             }
         }

app/src/main/java/no/naiv/implausibly/ui/navigation/AppNavHost.kt

@@ -3,19 +3,14 @@ package no.naiv.implausibly.ui.navigation
 
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
-import androidx.compose.runtime.collectAsState
-import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.remember
-import androidx.compose.runtime.setValue
 import androidx.navigation.NavType
 import androidx.navigation.compose.NavHost
 import androidx.navigation.compose.composable
 import androidx.navigation.compose.rememberNavController
 import androidx.navigation.navArgument
+import kotlinx.coroutines.flow.first
 import no.naiv.implausibly.data.AppPreferences
 import no.naiv.implausibly.data.repository.InstanceRepository
-import no.naiv.implausibly.data.repository.SiteRepository
 import no.naiv.implausibly.ui.common.LoadingIndicator
 import no.naiv.implausibly.ui.dashboard.DashboardScreen
 import no.naiv.implausibly.ui.setup.SetupScreen
@@ -25,42 +20,29 @@ import no.naiv.implausibly.ui.sites.SiteListScreen
  * App-level navigation host.
  *
  * On launch, checks DataStore for a previously selected instance/site.
- * If found, navigates directly to the dashboard (or site list if no site
+ * If found, navigates directly to the dashboard. Otherwise, shows setup.
- * is selected). Otherwise, shows the setup screen.
  */
 @Composable
 fun AppNavHost(
     appPreferences: AppPreferences,
-    instanceRepository: InstanceRepository,
+    instanceRepository: InstanceRepository
-    siteRepository: SiteRepository
 ) {
     val navController = rememberNavController()
 
-    // Collect saved preferences to determine start destination
-    val savedInstanceId by appPreferences.selectedInstanceId.collectAsState(initial = null)
-    val savedSiteId by appPreferences.selectedSiteId.collectAsState(initial = null)
-    var hasNavigated by remember { mutableStateOf(false) }
-
     NavHost(
         navController = navController,
         startDestination = Routes.LOADING
     ) {
-        // Loading screen — resolves start destination from preferences
         composable(Routes.LOADING) {
             LoadingIndicator()
 
-            LaunchedEffect(savedInstanceId, savedSiteId) {
+            // Use flow.first() to suspend until DataStore actually loads
-                // Wait for preferences to load (initial null vs actual null)
+            LaunchedEffect(Unit) {
-                // Once we have a value (even if null), navigate
+                val instanceId = appPreferences.selectedInstanceId.first()
-                if (hasNavigated) return@LaunchedEffect
+                val siteId = appPreferences.selectedSiteId.first()
-                hasNavigated = true
-
-                val instanceId = savedInstanceId
-                val siteId = savedSiteId
 
                 val destination = when {
                     instanceId != null && siteId != null -> {
-                        // Verify the instance still exists
                         val instance = instanceRepository.getById(instanceId)
                         if (instance != null) {
                             Routes.dashboard(instanceId, siteId)