Fix CronJob model API compatibility and register BackHandler in SettingsScreen

app/src/main/java/com/m57/hermescontrol/ui/settings/SettingsScreen.kt

@@ -1,5 +1,6 @@
 package com.m57.hermescontrol.ui.settings
 
+import androidx.activity.compose.BackHandler
 import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.animation.fadeIn
 import androidx.compose.animation.fadeOut
@@ -66,6 +67,8 @@ fun SettingsScreen(
     val state by viewModel.uiState.collectAsStateWithLifecycle()
     var passwordVisible by remember { mutableStateOf(false) }
 
+    BackHandler(onBack = onBack)
+
     Scaffold(
         modifier = modifier.fillMaxSize(),
         topBar = {