fix(persistence): correctifs post-QA sur les repositories (ticket #13)

Corrige les ports, use cases, entités et l'implémentation Drift des
repositories suite aux retours de QA. flutter analyze propre, 24/24
tests verts, build APK debug validé.

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

lib/application/ports.dart

@@ -80,6 +80,7 @@ abstract interface class ActiveSessionRepository {
   Future<void> save(ActiveWorkoutSession session);
   Future<void> saveSetResult(ActiveSetResult result);
   Future<void> saveRestState(ActiveRestState restState);
+  Future<ActiveRestState?> findRestStateById(String id);
   Future<List<ActiveSetResult>> listSetResults(String sessionId);
   Future<List<ActiveRestState>> listRestStates(String sessionId);
 }

lib/application/use_cases.dart

@@ -803,6 +803,50 @@ final class ActiveWorkoutSessionUseCases {
     return rest;
   }
 
+  Future<ActiveRestState> adjustRestSeconds({
+    required String restStateId,
+    required int deltaSeconds,
+  }) async {
+    final rest = await sessionRepository.findRestStateById(restStateId);
+    if (rest == null) {
+      throw const DomainException('Active rest state not found.');
+    }
+    final now = clock.now();
+    final adjusted = rest.copyWith(
+      metadata: rest.metadata.touch(now),
+      adjustedRestSeconds: (rest.adjustedRestSeconds + deltaSeconds).clamp(
+        0,
+        1 << 31,
+      ),
+    );
+    await sessionRepository.saveRestState(adjusted);
+    return adjusted;
+  }
+
+  Future<ActiveRestState> skipRest({required String restStateId}) async {
+    final rest = await sessionRepository.findRestStateById(restStateId);
+    if (rest == null) {
+      throw const DomainException('Active rest state not found.');
+    }
+    final now = clock.now();
+    final skipped = rest.copyWith(
+      metadata: rest.metadata.touch(now),
+      skippedAt: now,
+    );
+    await sessionRepository.saveRestState(skipped);
+    return skipped;
+  }
+
+  Future<ActiveRestState?> findActiveRest({required String sessionId}) async {
+    final restStates = await sessionRepository.listRestStates(sessionId);
+    final active =
+        restStates
+            .where((rest) => rest.endedAt == null && rest.skippedAt == null)
+            .toList()
+          ..sort((left, right) => right.startedAt.compareTo(left.startedAt));
+    return active.isEmpty ? null : active.first;
+  }
+
   Future<ActiveWorkoutSession> _requiredSession(String sessionId) async {
     final session = await sessionRepository.findById(sessionId);
     if (session == null) {