fix: sql and redis request

backend/gestion/db/db_clients.go

@@ -292,6 +292,28 @@ func (d *Database) GetClientByTelephone(telephone string) (*models.Client, error
 }
 
 // GetClientByUsername récupère un client par son username
+// GetClientsByUsernames charge plusieurs clients en une seule requête.
+// Retourne map[username]*Client ; les usernames sans correspondance sont absents de la map.
+func (d *Database) GetClientsByUsernames(usernames []string) (map[string]*models.Client, error) {
+	result := make(map[string]*models.Client, len(usernames))
+	if len(usernames) == 0 {
+		return result, nil
+	}
+	var rows []struct {
+		ID       int    `gorm:"column:id"`
+		Username string `gorm:"column:username"`
+		Nom      string `gorm:"column:nom"`
+		Prenom   string `gorm:"column:prenom"`
+	}
+	if err := d.GDB.Raw(`SELECT id, username, nom, prenom FROM clients WHERE username IN ?`, usernames).Scan(&rows).Error; err != nil {
+		return nil, err
+	}
+	for _, r := range rows {
+		result[r.Username] = &models.Client{ID: r.ID, Username: r.Username, Nom: r.Nom, Prenom: r.Prenom}
+	}
+	return result, nil
+}
+
 func (d *Database) GetClientByUsername(username string) (*models.Client, error) {
 	var row struct {
 		ID                 int       `gorm:"column:id"`