feat(#159/#160): suppressions métier dashboard — API + UI (squash develop).

Matrice PO #154 : supprimer dossiers famille/AM, parents, enfants et comptes
staff avec règles métier (placements clôturés, sans_enfant, cascade foyer,
droits gestionnaire/admin). Poubelle en liste, dialogues de confirmation,
garde-fou gestionnaire→gestionnaire. Inclut polish hauteur modale fiche AM.

frontend/lib/services/user_service.dart

@@ -646,14 +646,93 @@ class UserService {
     return enrichEnfantParentNames(enfant);
   }
 
-  static Future<void> deleteEnfant(String enfantId) async {
+  /// DELETE /enfants/:id?deleteDossier= — ticket #159 / #160.
+  static Future<Map<String, dynamic>> deleteEnfant(
+    String enfantId, {
+    bool deleteDossier = false,
+  }) async {
+    final uri = Uri.parse(
+      '${ApiConfig.baseUrl}${ApiConfig.enfants}/$enfantId',
+    ).replace(
+      queryParameters: {
+        'deleteDossier': deleteDossier ? 'true' : 'false',
+      },
+    );
+    final response = await http.delete(uri, headers: await _headers());
+    if (response.statusCode != 200 && response.statusCode != 204) {
+      throw Exception(
+        _extractErrorMessage(response.body, 'Erreur suppression enfant'),
+      );
+    }
+    return _parseSuppressionBody(response.body);
+  }
+
+  /// DELETE /dossiers/:numeroDossier — ticket #159 / #160.
+  static Future<Map<String, dynamic>> deleteDossier(
+    String numeroDossier,
+  ) async {
+    final num = numeroDossier.trim();
+    if (num.isEmpty) {
+      throw Exception('Numéro de dossier manquant.');
+    }
+    final encoded = Uri.encodeComponent(num);
     final response = await http.delete(
-      Uri.parse('${ApiConfig.baseUrl}${ApiConfig.enfants}/$enfantId'),
+      Uri.parse('${ApiConfig.baseUrl}${ApiConfig.dossiers}/$encoded'),
       headers: await _headers(),
     );
     if (response.statusCode != 200 && response.statusCode != 204) {
-      throw Exception(_extractErrorMessage(response.body, 'Erreur suppression enfant'));
+      throw Exception(
+        _extractErrorMessage(response.body, 'Erreur suppression dossier'),
+      );
     }
+    return _parseSuppressionBody(response.body);
+  }
+
+  /// Liste unifiée GET /dossiers — flags `sans_enfant` (#159).
+  static Future<List<Map<String, dynamic>>> listDossiers({String? q}) async {
+    final uri = Uri.parse('${ApiConfig.baseUrl}${ApiConfig.dossiers}')
+        .replace(
+      queryParameters: (q != null && q.trim().isNotEmpty)
+          ? {'q': q.trim()}
+          : null,
+    );
+    final response = await http.get(uri, headers: await _headers());
+    if (response.statusCode != 200) {
+      throw Exception(
+        _extractErrorMessage(response.body, 'Erreur chargement dossiers'),
+      );
+    }
+    final decoded = jsonDecode(response.body);
+    if (decoded is! List) return const [];
+    return decoded
+        .whereType<Map>()
+        .map((e) => Map<String, dynamic>.from(e))
+        .toList();
+  }
+
+  /// Map `numero_dossier` → `sans_enfant` (familles uniquement).
+  static Future<Map<String, bool>> getSansEnfantByNumero() async {
+    final rows = await listDossiers();
+    final out = <String, bool>{};
+    for (final row in rows) {
+      final num = (row['numero_dossier'] ?? '').toString().trim();
+      if (num.isEmpty) continue;
+      final type = (row['type'] ?? '').toString().toLowerCase();
+      if (type != 'famille') continue;
+      out[num] = row['sans_enfant'] == true;
+    }
+    return out;
+  }
+
+  static Map<String, dynamic> _parseSuppressionBody(String body) {
+    if (body.trim().isEmpty) return <String, dynamic>{};
+    try {
+      final decoded = jsonDecode(body);
+      if (decoded is Map) {
+        return Map<String, dynamic>.from(decoded);
+      }
+    } catch (_) {}
+    return <String, dynamic>{};
   }
 
   /// AM dont la liste d'enfants actifs contient [enfantId] (API actuelle).
@@ -1224,22 +1303,18 @@ class UserService {
     return AppUser.fromJson(data);
   }
 
-  static Future<void> deleteUser(String userId) async {
+  /// DELETE /users/:id — cascades métier #159 / #160.
+  static Future<Map<String, dynamic>> deleteUser(String userId) async {
     final response = await http.delete(
       Uri.parse('${ApiConfig.baseUrl}${ApiConfig.users}/$userId'),
       headers: await _headers(),
     );
 
     if (response.statusCode != 200 && response.statusCode != 204) {
-      final decoded = jsonDecode(response.body);
-      if (decoded is Map<String, dynamic>) {
-        final message = decoded['message'];
-        if (message is List && message.isNotEmpty) {
-          throw Exception(message.join(' - '));
-        }
-        throw Exception(_toStr(message) ?? 'Erreur suppression utilisateur');
-      }
-      throw Exception('Erreur suppression utilisateur');
+      throw Exception(
+        _extractErrorMessage(response.body, 'Erreur suppression utilisateur'),
+      );
     }
+    return _parseSuppressionBody(response.body);
   }
 }