Stage 1: project setup, Exercise Library, both Mode designs and the Mode switch

- Flutter Android app on CookIT's stack (provider, shared_preferences, gen-l10n)
- tools/exercise-import turns free-exercise-db into 876 bundled Exercises
  with 1,746 WebP images (20 MB); stretching -> Stretching, rest -> Workout
- ZenStyle tokens per Mode: calm rounded sage/teal with breath ripples vs.
  dark ember-to-red with floor-tape slashes; the theme morphs at each
  Mode's own pace
- Remembered global Mode switch, Plans / Library / History tabs

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

lib/src/app.dart

@@ -0,0 +1,36 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_localizations/flutter_localizations.dart';
+import 'package:provider/provider.dart';
+
+import 'design/app_theme.dart';
+import 'design/zen_style.dart';
+import 'home/home_view.dart';
+import 'localization/app_localizations.dart';
+import 'settings/settings_controller.dart';
+
+class ZenXerciseApp extends StatelessWidget {
+  const ZenXerciseApp({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final mode = context.watch<SettingsController>().mode;
+    // The whole app morphs into the new Mode at that Mode's own pace.
+    final style = ZenStyle.forMode(mode);
+    return MaterialApp(
+      theme: AppTheme.forMode(mode),
+      themeAnimationDuration: style.motion,
+      themeAnimationCurve: style.curve,
+      restorationScopeId: 'app',
+      localizationsDelegates: const [
+        AppLocalizations.delegate,
+        GlobalMaterialLocalizations.delegate,
+        GlobalWidgetsLocalizations.delegate,
+        GlobalCupertinoLocalizations.delegate,
+      ],
+      supportedLocales: AppLocalizations.supportedLocales,
+      onGenerateTitle: (context) => AppLocalizations.of(context).appTitle,
+      onGenerateRoute: (settings) =>
+          MaterialPageRoute<Object?>(settings: settings, builder: (context) => const HomeView()),
+    );
+  }
+}