feat(ui): écran Création/édition de programme

Ajoute l'écran de programme (presentation/program_screen.dart) et un
écran d'accueil (presentation/home_screen.dart) pour la navigation,
avec les ajustements application/domaine/repositories nécessaires.
flutter analyze propre, 11/11 tests verts, build APK debug validé.

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

lib/application/use_cases.dart

@@ -227,6 +227,10 @@ final class ProgramUseCases {
   final IdGenerator ids;
   final String originDeviceId;
 
+  Future<Program?> findById(String id) => programRepository.findById(id);
+
+  Future<List<Program>> listActive() => programRepository.listActive();
+
   Future<Program> create({
     required String name,
     required int defaultRestSeconds,
@@ -241,6 +245,69 @@ final class ProgramUseCases {
     return program;
   }
 
+  Future<Program> saveConfigured({
+    String? id,
+    required String name,
+    required int defaultRestSeconds,
+    required List<ProgramExerciseConfig> exercises,
+  }) async {
+    final now = clock.now();
+    final existing = id == null ? null : await programRepository.findById(id);
+    if (id != null && existing == null) {
+      throw const DomainException('Program not found.');
+    }
+    final programId = id ?? ids.newId();
+    final metadata =
+        existing?.metadata.touch(now) ??
+        EntityMetadata(
+          id: programId,
+          createdAt: now,
+          updatedAt: now,
+          originDeviceId: originDeviceId,
+        );
+    final programExercises = <ProgramExercise>[];
+    for (var index = 0; index < exercises.length; index++) {
+      final input = exercises[index];
+      final exerciseMetadata =
+          input.existingMetadata?.touch(now) ??
+          _newMetadata(ids, originDeviceId, now);
+      programExercises.add(
+        ProgramExercise(
+          metadata: exerciseMetadata,
+          programId: programId,
+          sourceExerciseId: input.sourceExerciseId,
+          position: index,
+          exerciseNameSnapshot: input.exerciseNameSnapshot,
+          exerciseDescriptionSnapshot: input.exerciseDescriptionSnapshot,
+          exerciseImageMediaIdSnapshot: input.exerciseImageMediaIdSnapshot,
+          exerciseVideoMediaIdSnapshot: input.exerciseVideoMediaIdSnapshot,
+          exerciseArchivedSnapshot: input.exerciseArchivedSnapshot,
+          availableTimeSnapshot: input.availableTimeSnapshot,
+          availableRepsSnapshot: input.availableRepsSnapshot,
+          availableScoreSnapshot: input.availableScoreSnapshot,
+          scoreLabelSnapshot: input.scoreLabelSnapshot,
+          scoreUnitSnapshot: input.scoreUnitSnapshot,
+          setsCount: input.setsCount,
+          timeEnabled: input.enabledMeasures.contains(WorkoutMeasure.time),
+          repsEnabled: input.enabledMeasures.contains(WorkoutMeasure.reps),
+          scoreEnabled: input.enabledMeasures.contains(WorkoutMeasure.score),
+          targetTimeSeconds: input.targetTimeSeconds,
+          targetReps: input.targetReps,
+          targetScore: input.targetScore,
+          restSecondsOverride: input.restSecondsOverride,
+        ),
+      );
+    }
+    final program = Program(
+      metadata: metadata,
+      name: name,
+      defaultRestSeconds: defaultRestSeconds,
+      exercises: programExercises,
+    );
+    await programRepository.replaceExercises(program, now);
+    return program;
+  }
+
   Future<ProgramExercise> addExercise({
     required String programId,
     required String exerciseId,
@@ -274,6 +341,48 @@ final class ProgramUseCases {
   }
 }
 
+final class ProgramExerciseConfig {
+  const ProgramExerciseConfig({
+    this.existingMetadata,
+    this.sourceExerciseId,
+    required this.exerciseNameSnapshot,
+    this.exerciseDescriptionSnapshot,
+    this.exerciseImageMediaIdSnapshot,
+    this.exerciseVideoMediaIdSnapshot,
+    this.exerciseArchivedSnapshot = false,
+    required this.availableTimeSnapshot,
+    required this.availableRepsSnapshot,
+    required this.availableScoreSnapshot,
+    this.scoreLabelSnapshot,
+    this.scoreUnitSnapshot,
+    required this.setsCount,
+    required this.enabledMeasures,
+    this.targetTimeSeconds,
+    this.targetReps,
+    this.targetScore,
+    this.restSecondsOverride,
+  });
+
+  final EntityMetadata? existingMetadata;
+  final String? sourceExerciseId;
+  final String exerciseNameSnapshot;
+  final String? exerciseDescriptionSnapshot;
+  final String? exerciseImageMediaIdSnapshot;
+  final String? exerciseVideoMediaIdSnapshot;
+  final bool exerciseArchivedSnapshot;
+  final bool availableTimeSnapshot;
+  final bool availableRepsSnapshot;
+  final bool availableScoreSnapshot;
+  final String? scoreLabelSnapshot;
+  final String? scoreUnitSnapshot;
+  final int setsCount;
+  final Set<WorkoutMeasure> enabledMeasures;
+  final int? targetTimeSeconds;
+  final int? targetReps;
+  final double? targetScore;
+  final int? restSecondsOverride;
+}
+
 final class WorkoutTemplateUseCases {
   const WorkoutTemplateUseCases({
     required this.templateRepository,