feat(ui): affichage du chrono de score dans le plan et l'historique (ticket #28)

Affiche le chrono du score chronométré sur workout_execution_screen.dart
(plan de séance) et history_screen.dart (historique). flutter analyze
propre, 77/77 tests verts, build APK debug validé. Dernier ticket du
backlog — clôture aussi le ticket parent #18 (score chronométré).

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

test/presentation/workout_execution_screen_test.dart

@@ -673,6 +673,62 @@ void main() {
     expect(find.text('Plan de séance'), findsNothing);
   });
 
+  testWidgets('le plan affiche le score chrono formaté avec objectif', (
+    tester,
+  ) async {
+    final clock = _FakeClock(DateTime.utc(2026, 7, 17, 12));
+    final repository = _FakeActiveSessionRepository();
+    final session = ActiveWorkoutSession(
+      metadata: _metadata('session-1'),
+      sourceWorkoutTemplateId: 'template-1',
+      status: ActiveWorkoutStatus.running,
+      startedAt: DateTime.utc(2026, 7, 17, 12),
+      lastPersistedAt: DateTime.utc(2026, 7, 17, 12),
+      elapsedActiveMs: 0,
+      currentProgramIndex: 0,
+      currentExerciseIndex: 0,
+      currentSetIndex: 1,
+      resolvedTemplateSnapshotJson: _sessionSnapshot(
+        setsCount: 2,
+        restSeconds: 0,
+        scoreInputMode: ScoreInputMode.stopwatch,
+        targetScoreTimeMs: 45000,
+      ),
+    );
+    repository.session = session;
+    repository.results.add(
+      ActiveSetResult(
+        metadata: _metadata('result-1'),
+        activeWorkoutSessionId: 'session-1',
+        programSnapshotId: 'template-program-1',
+        exerciseSnapshotId: 'exercise-1',
+        programIndex: 0,
+        exerciseIndex: 0,
+        setIndex: 0,
+        actualScoreTimeMs: 38700,
+        scoreInputModeSnapshot: ScoreInputMode.stopwatch,
+      ),
+    );
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: WorkoutExecutionScreen(
+          initialSession: session,
+          activeUseCases: _activeUseCases(repository, clock),
+          closeUseCase: _closeUseCase(repository, clock),
+          historyUseCases: _historyUseCases(clock),
+          workoutTemplateUseCases: _workoutTemplateUseCases(),
+        ),
+      ),
+    );
+
+    await tester.tap(find.byTooltip('Voir le plan'));
+    await tester.pumpAndSettle();
+
+    expect(find.text('Score chrono 00:38.7 / objectif 00:45'), findsOneWidget);
+    expect(find.textContaining('Temps réalisé 00:38.7'), findsNothing);
+  });
+
   testWidgets(
     'modifier une série passée la termine sans changer la position courante',
     (tester) async {
@@ -836,6 +892,7 @@ String _sessionSnapshot({
   int targetTimeSeconds = 45,
   int targetReps = 10,
   double targetScore = 80,
+  int? targetScoreTimeMs,
   String scoreUnit = 'kg',
   ScoreInputMode scoreInputMode = ScoreInputMode.manual,
   List<String> imageMediaIds = const [],
@@ -859,6 +916,7 @@ String _sessionSnapshot({
               'targetTimeSeconds': targetTimeSeconds,
               'targetReps': targetReps,
               'targetScore': targetScore,
+              'targetScoreTimeMs': targetScoreTimeMs,
               'scoreInputModeSnapshot': scoreInputMode.name,
               'scoreLabelSnapshot': 'Score',
               'scoreUnitSnapshot': scoreUnit,