BrandButton.rised rewrite as SPBrandButton widget

lib/ui/components/buttons/brand_button.dart

@@ -7,8 +7,9 @@ class BrandButton {
     final String? text,
     final Widget? child,
   }) {
-    assert(text == null || child == null, 'required title or child');
-    assert(text != null || child != null, 'required title or child');
+    assert((text ?? child) != null, 'either title or child must not be empty');
+    assert(text != null || child != null, 'title or child must be provided');
+
     return ConstrainedBox(
       constraints: const BoxConstraints(
         minHeight: 48,
@@ -28,8 +29,9 @@ class BrandButton {
     final String? text,
     final Widget? child,
   }) {
-    assert(text == null || child == null, 'required title or child');
-    assert(text != null || child != null, 'required title or child');
+    assert((text ?? child) != null, 'either title or child must not be empty');
+    assert(text != null || child != null, 'title or child must be provided');
+
     return ConstrainedBox(
       constraints: const BoxConstraints(
         minWidth: double.infinity,

lib/ui/components/buttons/buttons.dart

@@ -0,0 +1,2 @@
+export 'brand_button.dart';
+export 'sp_brand_button.dart';

lib/ui/components/buttons/sp_brand_button.dart

@@ -0,0 +1,28 @@
+import 'package:flutter/material.dart';
+
+class SPBrandButton extends StatelessWidget {
+  const SPBrandButton({
+    required this.child,
+    required this.onPressed,
+    super.key,
+  });
+
+  SPBrandButton.text({
+    required final String title,
+    required this.onPressed,
+    super.key,
+  }) : child = Text(title);
+
+  final Widget child;
+  final VoidCallback onPressed;
+
+  @override
+  Widget build(final BuildContext context) => FilledButton(
+        // TODO(misterfourtytwo): move button styles to theme configuration
+        style: const ButtonStyle(
+          minimumSize: MaterialStatePropertyAll(Size.fromHeight(48)),
+        ),
+        onPressed: onPressed,
+        child: child,
+      );
+}