feat(server): implemente synchronisation et serveur avec fixtures (#187)

- Implémente la couche de synchronisation avec le serveur
- Ajoute les fixtures versionnées pour les tests
- Met à jour Drift database et repositories pour le support sync
- Améliore les tests de synchronisation
- Corrige et améliore le watch companion pour la collecte de métriques

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

lib/presentation/workout_execution_screen.dart

@@ -2332,7 +2332,7 @@ final class _LiveSensorBar extends StatelessWidget {
           _LiveSensorPill(
             icon: Icons.directions_run,
             label: _distanceMetricLabel(sensorState),
-            muted: _distanceLabel(sensorState) == null,
+            muted: !_isDistanceAvailable(sensorState),
           ),
           _LiveSensorPill(
             icon: Icons.local_fire_department,
@@ -5332,6 +5332,9 @@ String _heartRateMetricLabel(ActiveWorkoutSensorState? state) {
 }
 
 String _distanceMetricLabel(ActiveWorkoutSensorState? state) {
+  if (!_isDistanceAvailable(state)) {
+    return _sensorUnavailableLabel(state);
+  }
   return _distanceLabel(state) ?? _sensorUnavailableLabel(state);
 }
 
@@ -5357,6 +5360,12 @@ String? _distanceLabel(ActiveWorkoutSensorState? state) {
   return '${meters.round()} m';
 }
 
+bool _isDistanceAvailable(ActiveWorkoutSensorState? state) {
+  return state != null &&
+      state.latestDistanceAvailable &&
+      _distanceLabel(state) != null;
+}
+
 String? _caloriesLabel(ActiveWorkoutSensorState? state) {
   final actualCalories = state?.latestCaloriesKcal;
   if (actualCalories != null && actualCalories >= 0) {