feat(gestion): suppression en cascade exercice/programme/séance-modèle (ticket #37)

Ajoute la suppression avec gestion des dépendances en cascade sur les
écrans bibliothèque d'exercices, programme et séance-modèle, avec les
use cases et le bootstrap applicatif associés. flutter analyze propre,
58/58 tests verts, build APK debug validé.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

test/presentation/workout_template_screen_test.dart

@@ -69,6 +69,7 @@ void main() {
             programUseCases: ProgramUseCases(
               programRepository: programRepository,
               exerciseRepository: _FakeExerciseRepository(),
+              templateRepository: templateRepository,
               clock: clock,
               ids: _FakeIds(),
               originDeviceId: 'device-1',
@@ -108,6 +109,81 @@ void main() {
       expect(activeRepository.saveCount, 0);
     },
   );
+
+  testWidgets(
+    'supprimer une séance demande confirmation puis la retire de la liste',
+    (tester) async {
+      final clock = _FakeClock(DateTime.utc(2026, 7, 17, 12));
+      final templateRepository = _FakeWorkoutTemplateRepository([
+        _workoutTemplate(),
+      ]);
+      final activeRepository = _FakeActiveSessionRepository();
+      final programRepository = _FakeProgramRepository();
+      final historyRepository = _FakeWorkoutHistoryRepository();
+
+      await tester.pumpWidget(
+        MaterialApp(
+          home: WorkoutTemplateListScreen(
+            workoutTemplateUseCases: WorkoutTemplateUseCases(
+              templateRepository: templateRepository,
+              programRepository: programRepository,
+              clock: clock,
+              ids: _FakeIds(),
+              originDeviceId: 'device-1',
+            ),
+            programUseCases: ProgramUseCases(
+              programRepository: programRepository,
+              exerciseRepository: _FakeExerciseRepository(),
+              templateRepository: templateRepository,
+              clock: clock,
+              ids: _FakeIds(),
+              originDeviceId: 'device-1',
+            ),
+            activeUseCases: ActiveWorkoutSessionUseCases(
+              sessionRepository: activeRepository,
+              templateRepository: templateRepository,
+              clock: clock,
+              ids: _FakeIds(),
+              originDeviceId: 'device-1',
+            ),
+            closeUseCase: CloseWorkoutSessionUseCase(
+              sessionRepository: activeRepository,
+              historyRepository: historyRepository,
+              clock: clock,
+              ids: _FakeIds(),
+              originDeviceId: 'device-1',
+            ),
+            historyUseCases: WorkoutHistoryUseCases(
+              repository: historyRepository,
+              clock: clock,
+            ),
+          ),
+        ),
+      );
+      await tester.pump();
+      await tester.pump();
+
+      await tester.tap(find.byTooltip('Supprimer la séance'));
+      await tester.pumpAndSettle();
+
+      expect(find.text('Supprimer Séance jambes ?'), findsOneWidget);
+      expect(find.text('Cette action est irréversible.'), findsOneWidget);
+
+      await tester.tap(find.text('Annuler'));
+      await tester.pumpAndSettle();
+
+      expect(find.text('Séance jambes'), findsOneWidget);
+      expect(templateRepository.saved, isEmpty);
+
+      await tester.tap(find.byTooltip('Supprimer la séance'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.widgetWithText(FilledButton, 'Supprimer'));
+      await tester.pumpAndSettle();
+
+      expect(find.text('Séance jambes'), findsNothing);
+      expect(templateRepository.saved.single.metadata.deletedAt, isNotNull);
+    },
+  );
 }
 
 WorkoutTemplate _workoutTemplate() {
@@ -201,6 +277,7 @@ final class _FakeWorkoutTemplateRepository
   _FakeWorkoutTemplateRepository(this.templates);
 
   final List<WorkoutTemplate> templates;
+  final saved = <WorkoutTemplate>[];
 
   @override
   Future<WorkoutTemplate?> findById(String id) async {
@@ -211,16 +288,27 @@ final class _FakeWorkoutTemplateRepository
   }
 
   @override
-  Future<List<WorkoutTemplate>> listActive() async => templates;
+  Future<List<WorkoutTemplate>> listActive() async {
+    return templates
+        .where((template) => template.metadata.deletedAt == null)
+        .toList();
+  }
 
   @override
   Future<void> replaceComposition(
     WorkoutTemplate template,
     DateTime deletedAt,
-  ) async {}
+  ) async {
+    templates.removeWhere((item) => item.metadata.id == template.metadata.id);
+    templates.add(template);
+  }
 
   @override
-  Future<void> save(WorkoutTemplate template) async {}
+  Future<void> save(WorkoutTemplate template) async {
+    saved.add(template);
+    templates.removeWhere((item) => item.metadata.id == template.metadata.id);
+    templates.add(template);
+  }
 
   @override
   Future<void> saveOverride(WorkoutTemplateExerciseOverride override) async {}