fix(main): compose the main route only after preferences load

Show a blank frame until the first preferences snapshot arrives,
so the saved bar position does not flash or jump on cold start.

app/src/main/java/com/example/research/ui/main/MainScreen.kt

@@ -47,6 +47,10 @@ fun MainRoute(
 
     val settingsState by settingsViewModel.uiState.collectAsStateWithLifecycle()
     val searchQuery by searchViewModel.searchQuery.collectAsStateWithLifecycle()
+    if (!settingsState.hasLoadedPreferences) {
+        Box(modifier = Modifier.fillMaxSize())
+        return
+    }
     val isSearchBarAtBottom = settingsState.searchBarPosition == "BOTTOM"
 
     val scrollPosition = remember(searchViewModel) {

app/src/main/java/com/example/research/ui/settings/SettingsUiState.kt

@@ -25,6 +25,7 @@ data class SettingsUiState(
     val importState: ImportState = ImportState.Idle,
     val dictionarySources: List<DictionarySource> = emptyList(),
     val hasCompletedStartupScan: Boolean = false,
+    val hasLoadedPreferences: Boolean = false,
     val pipelineIdle: Boolean = true,
     val appVersion: String = "1.0",
 )

app/src/main/java/com/example/research/ui/settings/SettingsViewModel.kt

@@ -54,6 +54,7 @@ private data class OperationStateInputs(
     val isLanguageExpanded: Boolean,
     val isSearchBarExpanded: Boolean,
     val isDictionariesExpanded: Boolean,
+    val hasLoadedPreferences: Boolean,
 )
 
 class SettingsViewModel(
@@ -163,6 +164,7 @@ class SettingsViewModel(
                 preferencesManager.isLanguageExpanded,
                 preferencesManager.isSearchBarExpanded,
                 preferencesManager.isDictionariesExpanded,
+                hasLoadedPreferences,
             ) { params: Array<Any> ->
                 @Suppress("UNCHECKED_CAST")
                 OperationStateInputs(
@@ -176,6 +178,7 @@ class SettingsViewModel(
                     isLanguageExpanded = params[7] as Boolean,
                     isSearchBarExpanded = params[8] as Boolean,
                     isDictionariesExpanded = params[9] as Boolean,
+                    hasLoadedPreferences = params[10] as Boolean,
                 )
             }
 
@@ -254,6 +257,7 @@ class SettingsViewModel(
                     importState = operationState.importState,
                     dictionaryStatus = operationState.dictionaryStatus,
                     hasCompletedStartupScan = operationState.hasCompletedStartupScan,
+                    hasLoadedPreferences = operationState.hasLoadedPreferences,
                     pipelineIdle = !isIndexing &&
                         !operationState.downloadState.isActive &&
                         !operationState.importState.isActive,
@@ -293,6 +297,7 @@ class SettingsViewModel(
                 } catch (e: Exception) {
                     android.util.Log.w("SettingsViewModel", "Failed to load search bar position: ${e.message}")
                 }
+                hasLoadedPreferences.value = true
                 hasCompletedStartupScan.value = true
                 preferencesManager.setHadNoDictionaries(
                     localDictionaryRepository.dictionaries.value.isEmpty()