Start to build app skeleton

moneymgr_mobile/lib/utils/theme_utils.dart

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+import 'package:flutter/material.dart';
+
+/// Creates two [ThemeData]s (light and dark variants) from a given [seedColor].
+///
+/// This method is needed because once a [ThemeData] is generated, we cannot get
+/// the [ColorScheme] seed to generate another one based on the same seed.
+(ThemeData, ThemeData) createDualThemeData({
+  required Color seedColor,
+  TextTheme? textTheme,
+  bool? useMaterial3,
+  ThemeData Function(ThemeData)? transformer,
+}) {
+  var lightTheme = ThemeData.from(
+    colorScheme: ColorScheme.fromSeed(
+      seedColor: seedColor,
+      brightness: Brightness.light,
+    ),
+    textTheme: textTheme,
+    useMaterial3: useMaterial3,
+  );
+  var darkTheme = ThemeData.from(
+    colorScheme: ColorScheme.fromSeed(
+      seedColor: seedColor,
+      brightness: Brightness.dark,
+    ),
+    textTheme: textTheme,
+    useMaterial3: useMaterial3,
+  );
+
+  if (transformer != null) {
+    lightTheme = transformer(lightTheme);
+    darkTheme = transformer(darkTheme);
+  }
+
+  return (lightTheme, darkTheme);
+}