Feat: Macht die Kontoauswahl funktional

lib/Pages/Misc/floating_creation_button.dart

@@ -0,0 +1,65 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_expandable_fab/flutter_expandable_fab.dart';
+
+import '../../Controller/account_controller.dart';
+
+/// Ein Floating Action Button, der beim Klicken ein expandierendes Menü öffnet,
+/// um neue Transaktionen oder Konten anzulegen.
+class FloatingCreationButton extends StatefulWidget {
+  /// Erstellt eine neue Instanz dieser Klasse
+  const FloatingCreationButton({super.key});
+
+  @override
+  State<FloatingCreationButton> createState() => _FloatingCreationButtonState();
+}
+
+class _FloatingCreationButtonState extends State<FloatingCreationButton> {
+  final AccountController _accountController = AccountController();
+
+  @override
+  Widget build(final BuildContext context) => ExpandableFab(
+    openButtonBuilder: RotateFloatingActionButtonBuilder(
+      child: const Icon(Icons.add),
+    ),
+    type: ExpandableFabType.up,
+    childrenAnimation: ExpandableFabAnimation.none,
+    distance: 70,
+    children: <Widget>[
+      _expandableButton(
+        label: 'Neue Transaktion',
+        icon: Icons.add,
+        onPressed: () {},
+      ),
+      _expandableButton(
+        label: 'Neues Konto',
+        icon: Icons.account_balance_wallet,
+        onPressed: () {
+          _accountController.newAccountHandler(context);
+        },
+      ),
+    ],
+  );
+
+  Widget _expandableButton({
+    required final String label,
+    required final IconData icon,
+    required final VoidCallback onPressed,
+  }) => GestureDetector(
+    onTap: onPressed,
+    child: Row(
+      children: <Widget>[
+        Container(
+          padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
+          decoration: BoxDecoration(borderRadius: BorderRadius.circular(8)),
+          child: Text(label),
+        ),
+        const SizedBox(width: 12),
+        FloatingActionButton.small(
+          heroTag: null,
+          onPressed: onPressed,
+          child: Icon(icon),
+        ),
+      ],
+    ),
+  );
+}