feat(ui): écran Exécution de séance

Ajoute l'écran d'exécution de séance (presentation/workout_execution_screen.dart),
avec les ajustements application/domaine/repositories nécessaires et la
navigation depuis l'accueil et l'écran séance-modèle. flutter analyze
propre, 15/15 tests verts, build APK debug validé.

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

lib/application/app_bootstrap.dart

@@ -8,6 +8,8 @@ final class AppBootstrap {
     required this.mediaUseCases,
     required this.programUseCases,
     required this.workoutTemplateUseCases,
+    required this.activeWorkoutSessionUseCases,
+    required this.closeWorkoutSessionUseCase,
   });
 
   final AppDatabase database;
@@ -15,6 +17,8 @@ final class AppBootstrap {
   final MediaUseCases mediaUseCases;
   final ProgramUseCases programUseCases;
   final WorkoutTemplateUseCases workoutTemplateUseCases;
+  final ActiveWorkoutSessionUseCases activeWorkoutSessionUseCases;
+  final CloseWorkoutSessionUseCase closeWorkoutSessionUseCase;
 
   static Future<AppBootstrap> create() async {
     final database = AppDatabase.open();
@@ -23,6 +27,8 @@ final class AppBootstrap {
     final mediaRepository = DriftMediaAssetRepository(database);
     final programRepository = DriftProgramRepository(database);
     final templateRepository = DriftWorkoutTemplateRepository(database);
+    final activeSessionRepository = DriftActiveSessionRepository(database);
+    final historyRepository = DriftWorkoutHistoryRepository(database);
     final ids = LocalIdGenerator();
     const clock = SystemClock();
     const originDeviceId = 'local-device';
@@ -57,6 +63,20 @@ final class AppBootstrap {
         ids: ids,
         originDeviceId: originDeviceId,
       ),
+      activeWorkoutSessionUseCases: ActiveWorkoutSessionUseCases(
+        sessionRepository: activeSessionRepository,
+        templateRepository: templateRepository,
+        clock: clock,
+        ids: ids,
+        originDeviceId: originDeviceId,
+      ),
+      closeWorkoutSessionUseCase: CloseWorkoutSessionUseCase(
+        sessionRepository: activeSessionRepository,
+        historyRepository: historyRepository,
+        clock: clock,
+        ids: ids,
+        originDeviceId: originDeviceId,
+      ),
     );
   }