Comprehensive code review fixes: memory safety, resource management, and GTK4 modernization#5

Draft

Copilot wants to merge 3 commits intomainfrom

copilot/fix-25e4766f-60e3-4c3e-9008-ba8b38a9e8f3

Commits on Sep 17, 2025

Initial plan
Copilot
committed
Fix critical backend issues: memory leaks, resource management, and input validation

Copilot
and
Batuhan4
committed
Address deprecated GTK4 APIs and improve socket handling with signal handlers

Copilot
and
Batuhan4
committed