Add view and logik

lib/controllers/signin_controller.dart

@@ -0,0 +1,39 @@
+import 'package:flutter/material.dart';
+import 'package:get/get.dart';
+
+class SignInController extends GetxController {
+  final usernameController = TextEditingController();
+  final passwordController = TextEditingController();
+
+  @override
+  void onClose() {
+    usernameController.dispose();
+    passwordController.dispose();
+    super.onClose();
+  }
+
+  Future<void> registerUser() async {
+    final username = usernameController.text.trim();
+    final password = passwordController.text.trim();
+
+    if (username.isEmpty || password.isEmpty) {
+      Get.snackbar(
+        'Fehler',
+        'Bitte alle Felder ausfüllen',
+        snackPosition: SnackPosition.BOTTOM,
+        backgroundColor: Get.theme.colorScheme.error.withAlpha(26),
+        colorText: Get.theme.colorScheme.error,
+      );
+      return;
+    }
+
+    // TODO: Registrierungs-Logik implementieren
+    Get.snackbar(
+      'Erfolg',
+      'Benutzer "$username" wurde angelegt',
+      snackPosition: SnackPosition.BOTTOM,
+      backgroundColor: Get.theme.colorScheme.primary.withAlpha(26),
+      colorText: Get.theme.colorScheme.primary,
+    );
+  }
+}