fix(settings): let back leave a settings sub-screen, not all of Settings (#81)

The settings sub-screens are overlays over the hub, so each has to take the back
gesture itself; the hub's handler pops the whole Settings destination. Views and
Special dates never passed predictiveBack, so back there fell through to the hub
and dropped you on the calendar. Appearance, Event form and Notifications
already did the right thing.

app/src/main/java/de/jeanlucmakiola/calendula/ui/settings/SettingsScreen.kt

@@ -862,6 +862,7 @@ private fun ViewsScreen(
     CollapsingScaffold(
         title = stringResource(R.string.settings_section_views),
         onBack = onBack,
+        predictiveBack = true,
     ) {
         val config = state.quickSwitchConfig
 
@@ -1403,6 +1404,7 @@ private fun SpecialDatesScreen(
     CollapsingScaffold(
         title = stringResource(R.string.settings_section_special_dates),
         onBack = onBack,
+        predictiveBack = true,
     ) {
         // Paused banner: the permission was revoked after enabling.
         if (state.enabled && state.stalledPermission) {