Halkyon's shared packages

A pub workspace of the Dart packages Halkyon's apps share: halkyon_ui,
Halkyon's look (the theme, fonts, layout and shared widgets, with texts
in English and German), halkyon_core's low-level primitives and
halkyon_interop's cross-app contracts. Dart 3.13 with LeanCode's lints,
configured once at the root; apps take a package by git, pinned to a
signed commit.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

packages/halkyon_ui/example/lib/main.dart

@@ -0,0 +1,75 @@
+import 'package:halkyon_ui/halkyon_ui.dart';
+import 'package:material_ui/material_ui.dart';
+
+void main() {
+  registerFontLicenses();
+  runApp(const ExampleApp());
+}
+
+/// An app set up as Halkyon's are: the shared theme in both brightnesses,
+/// the package's texts beside Material's (from material_ui, whose own
+/// delegates serve its widgets), and snack bars fitted to the window.
+class const ExampleApp({
+  /// The language, the device's when null.
+  final Locale? locale,
+  super.key,
+}) extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) => MaterialApp(
+    title: 'Halkyon Example',
+    theme: appTheme(Brightness.light),
+    darkTheme: appTheme(Brightness.dark),
+    locale: locale,
+    localizationsDelegates: const [
+      HalkyonUiLocalizations.delegate,
+      ...GlobalMaterialLocalizations.delegates,
+    ],
+    supportedLocales: HalkyonUiLocalizations.supportedLocales,
+    builder: (context, child) => FittedSnackBars(child: child!),
+    home: const _Home(),
+  );
+}
+
+class const _Home() extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    final scheme = Theme.of(context).colorScheme;
+    return TopGradient(
+      background: scheme.surface,
+      child: Scaffold(
+        backgroundColor: Colors.transparent,
+        appBar: AppBar(backgroundColor: Colors.transparent),
+        body: Center(
+          child: ConstrainedBox(
+            constraints: const BoxConstraints(
+              maxWidth: readableContentMaxWidth,
+            ),
+            child: Padding(
+              padding: const EdgeInsets.all(16),
+              child: Column(
+                mainAxisSize: MainAxisSize.min,
+                children: [
+                  const BrandWordmark(product: 'Example'),
+                  const SizedBox(height: 24),
+                  SectionCard(
+                    child: Builder(
+                      builder: (context) => FilledButton.tonal(
+                        onPressed: () => confirmDestructiveAction(
+                          context,
+                          title: 'Delete everything?',
+                          message: 'It can’t be undone.',
+                          confirmLabel: 'Delete',
+                        ),
+                        child: const Text('Delete'),
+                      ),
+                    ),
+                  ),
+                ],
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+}