M7g: feature cleanups after the design-system fix pass

Resource-backed snackbars (showKvittSnackbar) in account, onboarding and
settings; SettingsScaffold replaced by KvittScaffold + SettingsMessageEffect.
KvittButton(loading) for S-6 saving and S-16 Synka nu. S-10 missing state
disables Synka nu offline (connectivity in the ViewModel, new
detail_missing_offline goldens). S-6 system back asks to discard unsaved
changes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TQd3pEP9UeN2uifbHknQ7B

android/feature/account/src/main/kotlin/se/hagstedt/kvitt/feature/account/AccountDetailScreen.kt

@@ -10,7 +10,6 @@ import androidx.compose.foundation.lazy.LazyListState
 import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.SnackbarDuration
 import androidx.compose.material3.SnackbarHostState
 import androidx.compose.material3.SnackbarResult
 import androidx.compose.runtime.Composable
@@ -22,6 +21,7 @@ import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.platform.LocalResources
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.unit.IntOffset
 import androidx.compose.ui.window.Popup
@@ -44,6 +44,7 @@ import se.hagstedt.kvitt.design.component.ProvideHousehold
 import se.hagstedt.kvitt.design.component.TopBarNavigation
 import se.hagstedt.kvitt.design.component.kvittLanguage
 import se.hagstedt.kvitt.design.component.ratioSpoken
+import se.hagstedt.kvitt.design.component.showKvittSnackbar
 import se.hagstedt.kvitt.design.format.MoneyFormatter
 import se.hagstedt.kvitt.design.icon.KvittIcon
 import se.hagstedt.kvitt.model.AccountId
@@ -273,16 +274,17 @@ private fun DeleteDialog(name: String, actions: AccountDetailActions) {
 /** Shows [message] once (4 s, 10 s with an action, design-spec §3.11); "Försök igen" repeats the failed action. */
 @Composable
 private fun MessageEffect(message: AccountMessage, host: SnackbarHostState, actions: AccountDetailActions) {
-    val text = when (message) {
-        is AccountMessage.CouldNotReach -> stringResource(DesignR.string.common_could_not_reach_server)
-        is AccountMessage.Restored -> stringResource(R.string.account_unarchived_snackbar, message.name)
-        AccountMessage.DeleteBlocked -> stringResource(R.string.account_delete_blocked)
-        AccountMessage.NeedsConnection -> stringResource(DesignR.string.common_needs_connection)
-        is AccountMessage.Failed -> errorText(message.code)
-    }
-    val action = if (message is AccountMessage.CouldNotReach) stringResource(DesignR.string.common_retry) else null
-    LaunchedEffect(message, text, action) {
-        val result = host.showSnackbar(text, action, duration = if (action != null) SnackbarDuration.Long else SnackbarDuration.Short)
+    val resources = LocalResources.current
+    LaunchedEffect(message) {
+        val (text, args) = when (message) {
+            is AccountMessage.CouldNotReach -> DesignR.string.common_could_not_reach_server to emptyList()
+            is AccountMessage.Restored -> R.string.account_unarchived_snackbar to listOf<Any>(message.name)
+            AccountMessage.DeleteBlocked -> R.string.account_delete_blocked to emptyList()
+            AccountMessage.NeedsConnection -> DesignR.string.common_needs_connection to emptyList()
+            is AccountMessage.Failed -> errorText(message.code) to emptyList()
+        }
+        val action = if (message is AccountMessage.CouldNotReach) DesignR.string.common_retry else null
+        val result = host.showKvittSnackbar(resources, text, args, action)
         if (result == SnackbarResult.ActionPerformed && message is AccountMessage.CouldNotReach) actions.onRetry(message.retry)
         actions.onMessageShown()
     }

android/feature/account/src/main/kotlin/se/hagstedt/kvitt/feature/account/AccountEditorScreen.kt

@@ -1,5 +1,6 @@
 package se.hagstedt.kvitt.feature.account
 
+import androidx.activity.compose.BackHandler
 import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
@@ -10,12 +11,9 @@ import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
-import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.verticalScroll
-import androidx.compose.material3.CircularProgressIndicator
 import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.SnackbarDuration
 import androidx.compose.material3.SnackbarHostState
 import androidx.compose.material3.SnackbarResult
 import androidx.compose.material3.Text
@@ -29,6 +27,7 @@ import androidx.compose.ui.draw.alpha
 import androidx.compose.ui.focus.FocusRequester
 import androidx.compose.ui.focus.focusRequester
 import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.platform.LocalResources
 import androidx.compose.ui.res.pluralStringResource
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.semantics.clearAndSetSemantics
@@ -54,6 +53,7 @@ import se.hagstedt.kvitt.design.component.TopBarNavigation
 import se.hagstedt.kvitt.design.component.kvittLanguage
 import se.hagstedt.kvitt.design.component.money
 import se.hagstedt.kvitt.design.component.ratioSpoken
+import se.hagstedt.kvitt.design.component.showKvittSnackbar
 import se.hagstedt.kvitt.design.format.MoneyFormatter
 import se.hagstedt.kvitt.design.icon.KvittIcon
 import se.hagstedt.kvitt.design.theme.KvittDimens
@@ -90,6 +90,8 @@ fun AccountEditorScreen(
         viewModel.savedHandled()
         onSaved(saved)
     }
+    // System back with unsaved changes asks first, as the close button does (design-spec S-6).
+    BackHandler(enabled = ui.dirty && !ui.discardDialog) { viewModel.requestClose() }
     val actions = AccountEditorActions(
         onClose = { if (viewModel.requestClose()) onClose() },
         onName = viewModel::onName,
@@ -142,13 +144,16 @@ fun AccountEditorContent(ui: AccountEditorUi, actions: AccountEditorActions, mod
     }
 }
 
-/** "Spara" (small filled); a progress indicator in its place while saving (design-spec S-6). */
+/** "Spara" (small filled); its in-button progress form while saving (design-spec S-6). */
 @Composable
 private fun SaveAction(ui: AccountEditorUi, actions: AccountEditorActions) {
-    Row(Modifier.padding(end = KvittTheme.spacing.s2), verticalAlignment = Alignment.CenterVertically, horizontalArrangement = Arrangement.spacedBy(KvittTheme.spacing.s2)) {
-        if (ui.saving) CircularProgressIndicator(Modifier.size(KvittDimens.iconButton), strokeWidth = KvittDimens.placeholderBorder)
-        KvittButton(stringResource(DesignR.string.common_save), actions.onSave, enabled = ui.canSave)
-    }
+    KvittButton(
+        stringResource(DesignR.string.common_save),
+        actions.onSave,
+        Modifier.padding(end = KvittTheme.spacing.s2),
+        enabled = ui.canSave || ui.saving,
+        loading = ui.saving,
+    )
 }
 
 @Composable
@@ -293,14 +298,15 @@ private const val PREVIEW_ORE = BP_TOTAL.toLong()
 
 @Composable
 private fun EditorMessageEffect(message: EditorMessage, host: SnackbarHostState, actions: AccountEditorActions) {
-    val text = when (message) {
-        EditorMessage.CouldNotReach -> stringResource(DesignR.string.common_could_not_reach_server)
-        EditorMessage.NeedsConnection -> stringResource(DesignR.string.common_needs_connection)
-        is EditorMessage.Failed -> errorText(message.code)
-    }
-    val action = if (message == EditorMessage.CouldNotReach) stringResource(DesignR.string.common_retry) else null
-    LaunchedEffect(message, text, action) {
-        val result = host.showSnackbar(text, action, duration = if (action != null) SnackbarDuration.Long else SnackbarDuration.Short)
+    val resources = LocalResources.current
+    LaunchedEffect(message) {
+        val text = when (message) {
+            EditorMessage.CouldNotReach -> DesignR.string.common_could_not_reach_server
+            EditorMessage.NeedsConnection -> DesignR.string.common_needs_connection
+            is EditorMessage.Failed -> errorText(message.code)
+        }
+        val action = if (message == EditorMessage.CouldNotReach) DesignR.string.common_retry else null
+        val result = host.showKvittSnackbar(resources, text, action = action)
         if (result == SnackbarResult.ActionPerformed) actions.onSave()
         actions.onMessageShown()
     }

android/feature/account/src/main/kotlin/se/hagstedt/kvitt/feature/account/Errors.kt

@@ -1,24 +1,19 @@
 package se.hagstedt.kvitt.feature.account
 
-import androidx.compose.runtime.Composable
-import androidx.compose.runtime.ReadOnlyComposable
-import androidx.compose.ui.res.stringResource
+import androidx.annotation.StringRes
 import se.hagstedt.kvitt.core.design.R as DesignR
 
 /** The snackbar text of an `OnlineResult.Failed` code without a field at fault (§14.3.2, strings.csv `error_*`). */
-@Composable
-@ReadOnlyComposable
-internal fun errorText(code: String): String = stringResource(
-    when (code) {
-        NETWORK -> DesignR.string.common_could_not_reach_server
-        "household_incomplete" -> DesignR.string.error_household_incomplete
-        "not_found" -> DesignR.string.error_not_found
-        "forbidden" -> DesignR.string.error_forbidden
-        "rate_limited" -> DesignR.string.error_rate_limited
-        "protocol_unsupported" -> DesignR.string.error_app_too_old
-        "internal", "unavailable", "not_implemented" -> DesignR.string.error_server
-        "validation_failed" -> DesignR.string.error_validation
-        "account_not_empty" -> R.string.account_delete_blocked
-        else -> DesignR.string.error_generic_invalid
-    },
-)
+@StringRes
+internal fun errorText(code: String): Int = when (code) {
+    NETWORK -> DesignR.string.common_could_not_reach_server
+    "household_incomplete" -> DesignR.string.error_household_incomplete
+    "not_found" -> DesignR.string.error_not_found
+    "forbidden" -> DesignR.string.error_forbidden
+    "rate_limited" -> DesignR.string.error_rate_limited
+    "protocol_unsupported" -> DesignR.string.error_app_too_old
+    "internal", "unavailable", "not_implemented" -> DesignR.string.error_server
+    "validation_failed" -> DesignR.string.error_validation
+    "account_not_empty" -> R.string.account_delete_blocked
+    else -> DesignR.string.error_generic_invalid
+}