refactor(#103): centralize navigation mutations through NavigationController.resetTo() (#164)

* refactor(#103): centralize navigation mutations through NavigationController.resetTo()

* fix(chat): fix scroll-to-bottom FAB compilation errors

app/src/main/java/com/m57/hermescontrol/Navigation.kt

@@ -326,8 +326,7 @@ fun MainNavigation(sessionId: String? = null) {
                         entry<ConnectScreen> {
                             ConnectScreenContent(
                                 onConnected = {
-                                    backStack.clear()
-                                    backStack.add(ChatScreen)
+                                    NavigationController.resetTo(ChatScreen)
                                 },
                                 modifier = Modifier.safeDrawingPadding(),
                             )

app/src/main/java/com/m57/hermescontrol/NavigationController.kt

@@ -49,8 +49,11 @@ object NavigationController {
         stack.add(key)
     }
 
-    fun add(key: NavKey) {
-        backStack?.add(key)
+    /** Clear the stack and navigate to the given screen atomically. */
+    fun resetTo(screen: NavKey) {
+        val stack = backStack ?: return
+        stack.clear()
+        stack.add(screen)
     }
 
     /**