How can a female student reconcile her reliance on Allah and her supplication to Him for success, despite her academic shortcomings, with the high grades her peers achieve without great effort? And is this considered a divine decree and a test, or a punishment for not taking the necessary means?

Everything that happens is by God's decree and destiny. Sins may cause calamities, but not every calamity is necessarily a punishment; it could be a trial. The success of others may be due to their intelligence, diligence, or it could be a trial from God for them. It is not permissible for a Muslim to have ill thoughts about God, for God decrees what He wills and does what He desires with wisdom. Academic failure does not mean failure in life, nor should it lead to despair or abandonment of worship. Success requires effort and taking the necessary means, along with having good thoughts about God, relying on Him, and seeking His help. The strong believer who is keen on what benefits him and seeks God's help is better than the weak one.