feat(#112): email accusé resoumission aux parents

Après PATCH reprise-resoumettre (parent), envoi à chaque parent du
dossier : confirmation resoumission + rappel numero_dossier.

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

backend/src/routes/auth/auth.service.ts

@@ -1004,7 +1004,7 @@ export class AuthService {
             dto.texte_motivation?.trim() ??
             dto.presentation_dossier?.trim();
 
-        return this.usersRepo.manager.transaction(async (manager) => {
+        const result = await this.usersRepo.manager.transaction(async (manager) => {
             const familyUsers = titulaire.numero_dossier
                 ? await manager.find(Users, {
                     where: {
@@ -1098,8 +1098,29 @@ export class AuthService {
                 statut: StatutUtilisateurType.EN_ATTENTE,
                 user_id: titulaireLive.id,
                 numero_dossier: titulaireLive.numero_dossier,
+                parentsPourEmail: familyUsers,
             };
         });
+
+        const numeroDossier = result.numero_dossier ?? '';
+        try {
+            for (const parent of result.parentsPourEmail) {
+                await this.mailService.sendResoumissionPendingEmail(
+                    parent.email,
+                    parent.prenom ?? '',
+                    parent.nom ?? '',
+                    numeroDossier,
+                );
+            }
+        } catch (err) {
+            this.logger.error(
+                "[resoumettreRepriseParent] Échec envoi email accusé resoumission (dossier conservé)",
+                err instanceof Error ? err.stack : String(err),
+            );
+        }
+
+        const { parentsPourEmail: _parentsPourEmail, ...response } = result;
+        return response;
     }
 
     private async resoumettreRepriseAM(