feat(j0.1): squelette projet Flutter + arborescence clean archi

- flutter create --platforms=android --org biz.siteop
- arborescence lib/core/{error,theme,router,di} et lib/features/{locking,playback,podcasts,parental,limits}/{domain,application,data,presentation}
- pubspec.yaml : flutter_riverpod ^2.6.1 (YAGNI — autres paquets aux jalons suivants)
- lib/main.dart : ProviderScope + StorytimeApp (MaterialApp + écran placeholder)
- test/app_boots_test.dart : TDD Red→Green vérifié (flutter test vert, flutter analyze 0 issue)
- README.md : prérequis Flutter 3.41.6 / Dart 3.11.4

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/main.dart

@@ -0,0 +1,25 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+void main() {
+  runApp(const ProviderScope(child: StorytimeApp()));
+}
+
+class StorytimeApp extends StatelessWidget {
+  const StorytimeApp({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Storytime',
+      home: Scaffold(
+        body: Center(
+          child: Text(
+            'Storytime',
+            style: Theme.of(context).textTheme.headlineLarge,
+          ),
+        ),
+      ),
+    );
+  }
+}