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/settings/settings_controller_test.dart

@@ -0,0 +1,25 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+import 'package:zenxercise/src/modes/mode.dart';
+import 'package:zenxercise/src/settings/settings_controller.dart';
+
+void main() {
+  test('starts in Stretching on first launch', () async {
+    SharedPreferences.setMockInitialValues({});
+    final settings = SettingsController(SettingsService());
+
+    await settings.loadSettings();
+
+    expect(settings.mode, Mode.stretching);
+  });
+
+  test('remembers the last-used Mode across launches', () async {
+    SharedPreferences.setMockInitialValues({});
+    await SettingsController(SettingsService()).updateMode(Mode.workout);
+
+    final relaunched = SettingsController(SettingsService());
+    await relaunched.loadSettings();
+
+    expect(relaunched.mode, Mode.workout);
+  });
+}