feat(online): partage client - use cases, inbox cache et import local (ticket #66)

Ajoute l'adapter API distant de partage (infrastructure/remote/share_api.dart)
et les use cases associés (application/use_cases.dart), avec cache
d'inbox et import local des ressources partagées acceptées. Étend le
modèle Drift (migration schemaVersion 11→12) et les entités du domaine
en conséquence. flutter pub get OK, build_runner OK, dart format
appliqué, analyze propre (mêmes infos préexistantes), 124/124 tests
verts, build APK debug validé.

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

lib/application/ports.dart

@@ -259,6 +259,69 @@ abstract interface class LocalSyncChangeRepository {
   Future<bool> applyRemoteItem(RemoteSyncedItem item);
 }
 
+final class RemoteShareSendResult {
+  const RemoteShareSendResult({
+    required this.shareId,
+    required this.recipientUserIds,
+    required this.unresolvedEmails,
+  });
+
+  final String shareId;
+  final List<String> recipientUserIds;
+  final List<String> unresolvedEmails;
+}
+
+enum ShareSendStatus { sent, notConnected, queued }
+
+final class ShareSendResult {
+  const ShareSendResult({
+    required this.status,
+    this.shareId,
+    this.recipientUserIds = const [],
+    this.unresolvedEmails = const [],
+    this.pendingActionId,
+  });
+
+  final ShareSendStatus status;
+  final String? shareId;
+  final List<String> recipientUserIds;
+  final List<String> unresolvedEmails;
+  final String? pendingActionId;
+}
+
+abstract interface class RemoteShareApi {
+  Future<RemoteShareSendResult> sendShare({
+    required ShareResourceType resourceType,
+    required Map<String, Object?> payload,
+    required List<String> recipientEmails,
+    required String token,
+  });
+
+  Future<List<ShareInboxItem>> fetchInbox(String token);
+  Future<RemoteSyncedItem> acceptShare(String shareId, String token);
+  Future<void> declineShare(String shareId, String token);
+  Future<void> revokeShare(String shareId, String token);
+}
+
+abstract interface class ShareInboxRepository {
+  Future<List<ShareInboxItem>> listAll();
+  Future<ShareInboxItem?> findByShareId(String shareId);
+  Future<void> upsert(ShareInboxItem item);
+  Future<void> upsertAll(List<ShareInboxItem> items);
+  Future<void> markStatus(
+    String shareId,
+    ShareInboxStatus status,
+    DateTime respondedAt,
+  );
+}
+
+abstract interface class PendingShareActionRepository {
+  Future<List<PendingShareAction>> listPending();
+  Future<void> add(PendingShareAction action);
+  Future<void> markSucceeded(String id, DateTime attemptedAt);
+  Future<void> markFailed(String id, DateTime attemptedAt);
+}
+
 const Object _portsUnchanged = Object();
 
 abstract interface class ExerciseRepository {