Autogenic Drainage Versus Mechanical Percussion in Children With Cystic Fibrosis

The goal of this clinical trial is to compare the effects of autogenic drainage and mechanical percussion on lung function, dyspnea, and quality of life in children with cystic fibrosis. The main questions it aims to answer are: * Does autogenic drainage improve lung function more effectively than mechanical percussion in children with cystic fibrosis? * Does autogenic drainage reduce dyspnea (breathlessness) more effectively than mechanical percussion? * Does autogenic drainage improve health-related quality of life more effectively than mechanical percussion? Researchers will compare autogenic drainage with mechanical percussion to determine which airway clearance technique provides greater benefits for children with cystic fibrosis. Participants will: * Be randomly assigned to receive either autogenic drainage or mechanical percussion therapy. * Participate in supervised treatmen