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>

test/views/home_view_test.dart

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+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:zenxercise/src/design/zen_style.dart';
+import 'package:zenxercise/src/home/home_view.dart';
+import 'package:zenxercise/src/modes/mode.dart';
+
+import '../support/test_app.dart';
+
+void main() {
+  ZenStyle styleOf(WidgetTester tester) => ZenStyle.of(tester.element(find.byType(HomeView)));
+
+  testWidgets('switching Mode changes design and Library together', (tester) async {
+    final settings = await pumpApp(tester);
+    await tester.tap(find.byTooltip('Library'));
+    await tester.pumpAndSettle();
+
+    expect(styleOf(tester).mode, Mode.stretching);
+    expect(find.text('2 stretches'), findsOneWidget);
+    expect(find.text('Hamstring Stretch'), findsOneWidget);
+
+    await tester.tap(find.text('Workout'));
+    await tester.pumpAndSettle();
+
+    expect(settings.mode, Mode.workout);
+    expect(styleOf(tester).mode, Mode.workout);
+    expect(styleOf(tester).brightness, Brightness.dark);
+    expect(find.text('1 exercise'), findsOneWidget);
+    expect(find.text('Barbell Squat'), findsOneWidget);
+    expect(find.text('Hamstring Stretch'), findsNothing);
+  });
+
+  testWidgets('opens in the last-used Mode', (tester) async {
+    await pumpApp(tester, prefs: {'mode': 'workout'});
+
+    expect(styleOf(tester).mode, Mode.workout);
+  });
+
+  testWidgets('an empty Plans tab invites building a Plan from the library', (tester) async {
+    await pumpApp(tester);
+
+    expect(find.text('No plans yet'), findsOneWidget);
+    expect(find.textContaining('stretch routine'), findsOneWidget);
+  });
+}