Security Audit Fixes: Session fixation prevention, SameSite cookies, audit log redaction, backup integrity, Docker hardening, error sanitization, rate limiting, trusted proxies, and config hardening

backend/internal/database/repositories/session.go

@@ -39,6 +39,11 @@ func (r *SessionRepository) Delete(id string) error {
 	return err
 }
 
+func (r *SessionRepository) DeleteByUserID(userID string) error {
+	_, err := r.db.Exec(`DELETE FROM sessions WHERE user_id = ?`, userID)
+	return err
+}
+
 func (r *SessionRepository) DeleteExpired() error {
 	_, err := r.db.Exec(`DELETE FROM sessions WHERE expires_at < ?`, time.Now())
 	return err