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/main.dart

@@ -0,0 +1,26 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:provider/provider.dart';
+
+import 'src/app.dart';
+import 'src/exercises/exercise_library.dart';
+import 'src/settings/settings_controller.dart';
+
+void main() async {
+  WidgetsFlutterBinding.ensureInitialized();
+  await SystemChrome.setPreferredOrientations([DeviceOrientation.portraitUp, DeviceOrientation.portraitDown]);
+
+  final library = await ExerciseLibrary.load(rootBundle);
+  final settings = SettingsController(SettingsService());
+  await settings.loadSettings();
+
+  runApp(
+    MultiProvider(
+      providers: [
+        ChangeNotifierProvider.value(value: settings),
+        Provider.value(value: library),
+      ],
+      child: const ZenXerciseApp(),
+    ),
+  );
+}