fix(#131): co_parent en réponse parents + masquage secrets user

Contrat API fiche parent : co_parent peuplé (déjà chargé), sans password
ni tokens sur user/co_parent. Doc tmp front→back.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/src/routes/parents/parents.mapper.spec.ts

@@ -0,0 +1,38 @@
+import { mapParentForApi } from './parents.mapper';
+import { Parents } from '../../entities/parents.entity';
+import { RoleType, StatutUtilisateurType, Users } from '../../entities/users.entity';
+
+describe('mapParentForApi', () => {
+  it('expose co_parent avec prenom/nom sans secrets', () => {
+    const coParent = {
+      id: 'cp1',
+      email: 'co@b.fr',
+      prenom: 'Clara',
+      nom: 'Co',
+      role: RoleType.PARENT,
+      statut: StatutUtilisateurType.ACTIF,
+      password: 'secret',
+    } as Users;
+
+    const parent = {
+      user_id: 'u1',
+      numero_dossier: '2026-000042',
+      user: {
+        id: 'u1',
+        email: 'p@b.fr',
+        prenom: 'Paul',
+        nom: 'Parent',
+        role: RoleType.PARENT,
+        password: 'secret',
+      } as Users,
+      co_parent: coParent,
+      parentChildren: [],
+    } as Parents;
+
+    const out = mapParentForApi(parent);
+    expect(out.co_parent?.prenom).toBe('Clara');
+    expect(out.co_parent?.nom).toBe('Co');
+    expect(out.co_parent?.password).toBeUndefined();
+    expect(out.user.password).toBeUndefined();
+  });
+});