feat(ui): écran Historique des séances

Ajoute l'écran d'historique des séances (presentation/history_screen.dart),
avec les ajustements application/domaine/repositories nécessaires et la
navigation depuis l'accueil. Complète le dernier écran du périmètre UI.
flutter analyze propre, 18/18 tests verts, build APK debug validé.

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

lib/application/use_cases.dart

@@ -638,6 +638,28 @@ final class ActiveWorkoutSessionUseCases {
     return session;
   }
 
+  Future<ActiveWorkoutSession> startFromHistory(WorkoutHistory history) async {
+    final snapshot =
+        jsonDecode(history.historySnapshotJson) as Map<String, dynamic>;
+    final resolvedTemplateSnapshotJson =
+        snapshot['resolvedTemplateSnapshotJson'] as String;
+    final now = clock.now();
+    final session = ActiveWorkoutSession(
+      metadata: _newMetadata(ids, originDeviceId, now),
+      sourceWorkoutTemplateId: null,
+      status: ActiveWorkoutStatus.running,
+      startedAt: now,
+      lastPersistedAt: now,
+      elapsedActiveMs: 0,
+      currentProgramIndex: 0,
+      currentExerciseIndex: 0,
+      currentSetIndex: 0,
+      resolvedTemplateSnapshotJson: resolvedTemplateSnapshotJson,
+    );
+    await sessionRepository.save(session);
+    return session;
+  }
+
   Future<ActiveWorkoutSession> pause(String sessionId) async {
     final session = await _requiredSession(sessionId);
     final paused = session.pause(clock.now());
@@ -851,6 +873,19 @@ final class CloseWorkoutSessionUseCase {
   }
 }
 
+final class WorkoutHistoryUseCases {
+  const WorkoutHistoryUseCases({required this.repository, required this.clock});
+
+  final WorkoutHistoryRepository repository;
+  final Clock clock;
+
+  Future<WorkoutHistory?> findById(String id) => repository.findById(id);
+
+  Future<List<WorkoutHistory>> listActive() => repository.listActive();
+
+  Future<void> delete(String id) => repository.delete(id, clock.now());
+}
+
 EntityMetadata _newMetadata(
   IdGenerator ids,
   String originDeviceId,