feat(communication): module messagerie unifié + contact policies + blocages

Aligné avec le backend MessagingResource :
- Nouveau module communication (conversations, messages, participants)
- Respect des ContactPolicy (qui peut parler à qui par rôle)
- Gestion MemberBlock (blocages individuels)
- UI : conversations list, conversation detail, broadcast, tiles
- BLoC : MessagingBloc avec events (envoyer, démarrer conversation rôle, etc.)

lib/features/communication/data/models/message_model.dart

@@ -1,83 +1,48 @@
-/// Model de données Message avec sérialisation JSON
+/// Modèle de données Message v4 avec désérialisation JSON
 library message_model;
 
-import 'package:json_annotation/json_annotation.dart';
 import '../../domain/entities/message.dart';
 
-part 'message_model.g.dart';
-
-@JsonSerializable(explicitToJson: true)
+/// Modèle Message v4
 class MessageModel extends Message {
   const MessageModel({
     required super.id,
-    required super.conversationId,
-    required super.senderId,
-    required super.senderName,
-    super.senderAvatar,
-    required super.content,
-    required super.type,
-    required super.status,
-    super.priority,
-    required super.recipientIds,
-    super.recipientRoles,
-    super.organizationId,
-    required super.createdAt,
-    super.readAt,
-    super.metadata,
-    super.attachments,
-    super.isEdited,
-    super.editedAt,
-    super.isDeleted,
+    required super.typeMessage,
+    super.contenu,
+    super.urlFichier,
+    super.dureeAudio,
+    super.supprime,
+    super.expediteurId,
+    super.expediteurNom,
+    super.expediteurPrenom,
+    super.messageParentId,
+    super.messageParentApercu,
+    super.dateEnvoi,
   });
 
-  factory MessageModel.fromJson(Map<String, dynamic> json) =>
-      _$MessageModelFromJson(json);
-
-  Map<String, dynamic> toJson() => _$MessageModelToJson(this);
-
-  factory MessageModel.fromEntity(Message message) {
+  factory MessageModel.fromJson(Map<String, dynamic> json) {
     return MessageModel(
-      id: message.id,
-      conversationId: message.conversationId,
-      senderId: message.senderId,
-      senderName: message.senderName,
-      senderAvatar: message.senderAvatar,
-      content: message.content,
-      type: message.type,
-      status: message.status,
-      priority: message.priority,
-      recipientIds: message.recipientIds,
-      recipientRoles: message.recipientRoles,
-      organizationId: message.organizationId,
-      createdAt: message.createdAt,
-      readAt: message.readAt,
-      metadata: message.metadata,
-      attachments: message.attachments,
-      isEdited: message.isEdited,
-      editedAt: message.editedAt,
-      isDeleted: message.isDeleted,
+      id: json['id']?.toString() ?? '',
+      typeMessage: json['typeMessage']?.toString() ?? 'TEXTE',
+      contenu: json['contenu']?.toString(),
+      urlFichier: json['urlFichier']?.toString(),
+      dureeAudio: _parseInt(json['dureeAudio']),
+      supprime: json['supprime'] == true,
+      expediteurId: json['expediteurId']?.toString(),
+      expediteurNom: json['expediteurNom']?.toString(),
+      expediteurPrenom: json['expediteurPrenom']?.toString(),
+      messageParentId: json['messageParentId']?.toString(),
+      messageParentApercu: json['messageParentApercu']?.toString(),
+      dateEnvoi: json['dateEnvoi'] != null
+          ? DateTime.tryParse(json['dateEnvoi'].toString())
+          : null,
     );
   }
-
-  Message toEntity() => Message(
-    id: id,
-    conversationId: conversationId,
-    senderId: senderId,
-    senderName: senderName,
-    senderAvatar: senderAvatar,
-    content: content,
-    type: type,
-    status: status,
-    priority: priority,
-    recipientIds: recipientIds,
-    recipientRoles: recipientRoles,
-    organizationId: organizationId,
-    createdAt: createdAt,
-    readAt: readAt,
-    metadata: metadata,
-    attachments: attachments,
-    isEdited: isEdited,
-    editedAt: editedAt,
-    isDeleted: isDeleted,
-  );
+}
+
+int? _parseInt(dynamic value) {
+  if (value == null) return null;
+  if (value is int) return value;
+  if (value is double) return value.toInt();
+  return int.tryParse(value.toString());
 }