feat(sprint-13.C mobile 2026-04-25): feature reporting (rapports trimestriels Contrôleur Interne)

Mobile mirror du backend P2-NEW-3. DRY strict — Clean Architecture identique aux autres features (compliance, devise).

Domain
- StatutRapport enum (draft, signe, archive, inconnu) + extension StatutRapportX (code/libelle/severite/fromCode)
- RapportTrimestriel entity (Equatable) + helpers libellePeriode, scoreSeverite (>=80 success, >=60 warning, <60 danger)

Data
- RapportTrimestrielModel.fromJson (parsing tolérant null + dates ISO)
- ReportingRemoteDataSourceImpl (Dio) : lister/generer/signer/archiver/telechargerPdf
- ReportingRepositoryImpl @Injectable

Presentation
- ReportingBloc : Load/Generer/Signer/Archiver events, 4 states (Initial/Loading/Loaded/Error)
- RapportsTrimestrielsPage : Material 3 ListView avec cards (period, score coloré, tag statut, hash tronqué) + EmptyView + ErrorView

Tests (10/10 verts)
- StatutRapportX × 2 (fromCode parse/null/inconnu, libelle/severite/code)
- RapportTrimestriel × 5 (libellePeriode, estDraft/estSigne/estArchive, scoreSeverite × 3)
- RapportTrimestrielModel.fromJson × 3 (complet, fallbacks, date invalide)

Note : viewer PDF interne reporté à un sprint dédié (intégration pdfx + permission storage Android). Téléchargement bytes via API exposé dans datasource pour usage futur.

lib/features/reporting/data/models/rapport_trimestriel_model.dart

@@ -0,0 +1,40 @@
+import '../../domain/entities/rapport_trimestriel.dart';
+
+class RapportTrimestrielModel extends RapportTrimestriel {
+  const RapportTrimestrielModel({
+    required super.id,
+    required super.organisationId,
+    required super.annee,
+    required super.trimestre,
+    required super.dateGeneration,
+    required super.statut,
+    required super.scoreConformite,
+    super.signataireId,
+    super.dateSignature,
+    super.hashSha256,
+  });
+
+  factory RapportTrimestrielModel.fromJson(Map<String, dynamic> json) {
+    return RapportTrimestrielModel(
+      id: json['id']?.toString() ?? '',
+      organisationId: json['organisationId']?.toString() ?? '',
+      annee: (json['annee'] as num?)?.toInt() ?? 0,
+      trimestre: (json['trimestre'] as num?)?.toInt() ?? 0,
+      dateGeneration: _parseDate(json['dateGeneration']),
+      statut: StatutRapportX.fromCode(json['statut']?.toString()),
+      scoreConformite: (json['scoreConformite'] as num?)?.toInt() ?? 0,
+      signataireId: json['signataireId']?.toString(),
+      dateSignature: _parseDate(json['dateSignature']),
+      hashSha256: json['hashSha256']?.toString(),
+    );
+  }
+
+  static DateTime? _parseDate(dynamic raw) {
+    if (raw == null) return null;
+    try {
+      return DateTime.parse(raw.toString());
+    } catch (_) {
+      return null;
+    }
+  }
+}