fix(#7): move DB/IO off main thread in ScreenModels

screenModelScope is backed by PlatformMainDispatcher (Main.immediate),
so direct interactor calls run DB queries and file I/O on the UI
thread. Switch reactive flows with .flowOn(Dispatchers.IO) and wrap
suspend calls in withContext(Dispatchers.IO).

app/src/main/java/dev/achmad/ledgerr/ui/screens/category/CategoryScreenModel.kt

@@ -7,10 +7,13 @@ import dev.achmad.ledgerr.domain.category.interactor.DeleteCategory
 import dev.achmad.ledgerr.domain.category.interactor.GetCategories
 import dev.achmad.ledgerr.domain.category.interactor.UpsertCategory
 import dev.achmad.ledgerr.domain.category.model.Category
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.flowOn
 import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 
 class CategoryScreenModel(
     private val getCategories: GetCategories = inject(),
@@ -19,6 +22,7 @@ class CategoryScreenModel(
 ) : ScreenModel {
 
     val categories: StateFlow<List<Category>> = getCategories.subscribeAll()
+        .flowOn(Dispatchers.IO)
         .stateIn(
             scope = screenModelScope,
             started = SharingStarted.Eagerly,
@@ -27,13 +31,17 @@ class CategoryScreenModel(
 
     fun upsert(category: Category) {
         screenModelScope.launch {
+            withContext(Dispatchers.IO) {
                 upsertCategory.await(category)
             }
         }
+    }
 
     fun delete(id: Long) {
         screenModelScope.launch {
+            withContext(Dispatchers.IO) {
                 runCatching { deleteCategory.await(id) }
             }
         }
     }
+}

app/src/main/java/dev/achmad/ledgerr/ui/screens/import_bank_statement/ImportBankStatementScreenModel.kt

@@ -11,6 +11,7 @@ import dev.achmad.ledgerr.domain.category.interactor.GetCategories
 import dev.achmad.ledgerr.domain.category.model.Category
 import dev.achmad.ledgerr.domain.expense.interactor.InsertExpenses
 import dev.achmad.ledgerr.domain.expense.model.Expense
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.SharedFlow
@@ -18,9 +19,11 @@ import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asSharedFlow
 import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.flowOn
 import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 
 sealed interface ImportState {
     data class BankPicker(val importers: List<BankStatementImporter>) : ImportState
@@ -44,6 +47,7 @@ class ImportBankStatementScreenModel(
     val snackbar: SharedFlow<String> = _snackbar.asSharedFlow()
 
     val categories: StateFlow<List<Category>> = getCategories.subscribeAll()
+        .flowOn(Dispatchers.IO)
         .stateIn(
             scope = screenModelScope,
             started = SharingStarted.Eagerly,
@@ -55,7 +59,9 @@ class ImportBankStatementScreenModel(
     fun processPdf(uri: Uri, importer: BankStatementImporter) {
         screenModelScope.launch {
             _state.value = ImportState.Processing(importer.bankName)
-            val result = importer.await(uri)
+            val result = withContext(Dispatchers.IO) {
+                importer.await(uri)
+            }
             result
                 .onSuccess { rows ->
                     if (rows.isEmpty()) {
@@ -105,14 +111,15 @@ class ImportBankStatementScreenModel(
     fun confirm(navigator: Navigator) {
         screenModelScope.launch {
             val confirmation = _state.value as? ImportState.Confirmation ?: return@launch
-            if (defaultCategoryId == 0L) {
-                defaultCategoryId = getCategories.awaitDefault().id
-            }
             val selected = confirmation.rows.filter { it.isSelected }
             if (selected.isEmpty()) {
                 _snackbar.tryEmit("No items selected")
                 return@launch
             }
+            withContext(Dispatchers.IO) {
+                if (defaultCategoryId == 0L) {
+                    defaultCategoryId = getCategories.awaitDefault().id
+                }
                 val expenses = selected.map { pending ->
                     Expense(
                         amount = pending.amount,
@@ -122,6 +129,7 @@ class ImportBankStatementScreenModel(
                     )
                 }
                 insertExpenses.awaitAll(expenses)
+            }
             navigator.pop()
         }
     }

app/src/main/java/dev/achmad/ledgerr/ui/screens/settings/SettingsScreenModel.kt

@@ -8,7 +8,9 @@ import dev.achmad.ledgerr.domain.category.interactor.SeedDefaultCategories
 import dev.achmad.ledgerr.domain.data.interactor.ClearAllData
 import dev.achmad.ledgerr.domain.expense.model.DateRange
 import dev.achmad.ledgerr.domain.export.interactor.ExportExpensesToCsv
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 
 class SettingsScreenModel(
     private val exportExpensesToCsv: ExportExpensesToCsv = inject(),
@@ -18,16 +20,21 @@ class SettingsScreenModel(
 
     fun exportToCsv(range: DateRange, uri: Uri, onResult: (Result<Unit>) -> Unit) {
         screenModelScope.launch {
-            onResult(exportExpensesToCsv.await(range, uri))
+            val result = withContext(Dispatchers.IO) {
+                exportExpensesToCsv.await(range, uri)
+            }
+            onResult(result)
         }
     }
 
     fun clearData(onResult: (Result<Unit>) -> Unit) {
         screenModelScope.launch {
-            val result = runCatching {
+            val result = withContext(Dispatchers.IO) {
+                runCatching {
                     clearAllData.await()
                     seedDefaultCategories.await()
                 }
+            }
             onResult(result)
         }
     }