refactor: Introduce ButtonThemes for component styling

This commit introduces a new `ButtonThemes` widget to centralize component theme overrides, following the pattern of `CardThemes` and `ContainerThemes`.

### Key Changes:

*   **`lib/screens/widgets/overrides/button_themes.dart`**:
    *   A new `ButtonThemes` widget is created. It wraps its child in a `ComponentTheme` to provide custom styling for buttons, specifically targeting `SecondaryButtonTheme`.

*   **`lib/screens/widgets/layouts/override_theme_layout.dart`**:
    *   The `OverrideThemeLayout` is updated to wrap its content with the new `ButtonThemes` widget, ensuring that custom button styles are applied consistently across the application.

Author: Lukas Gundermann

lib/screens/widgets/layouts/override_theme_layout.dart

@@ -1,5 +1,6 @@
 import 'package:shadcn_flutter/shadcn_flutter.dart';
 
+import '../overrides/button_themes.dart';
 import '../overrides/card_themes.dart';
 import '../overrides/container_themes.dart';
 
@@ -10,6 +11,8 @@ class OverrideThemeLayout extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return ContainerThemes(child: CardThemes(child: child));
+    return ButtonThemes(
+      child: ContainerThemes(child: CardThemes(child: child)),
+    );
   }
 }

lib/screens/widgets/overrides/button_themes.dart

@@ -0,0 +1,23 @@
+import 'package:shadcn_flutter/shadcn_flutter.dart';
+
+class ButtonThemes extends StatelessWidget {
+  const ButtonThemes({super.key, required this.child});
+
+  final Widget child;
+
+  @override
+  Widget build(BuildContext context) {
+    return ComponentTheme(
+      data: SecondaryButtonTheme(
+        decoration: (context, states, defaultDecoration) {
+          return defaultDecoration;
+          // return defaultDecoration.copyWithIfBoxDecoration(
+          //   color: Colors.red,
+          //   border: Border.all(color: Colors.green, width: 10),
+          // );
+        },
+      ),
+      child: child,
+    );
+  }
+}