Warn before overriding native system shortcuts

Maintain a hardcoded list of OS-reserved combos (Ctrl+C, Ctrl+V, Ctrl+X, Ctrl+A, Ctrl+Z, Ctrl+Y, Ctrl+S, Ctrl+F, Ctrl+P, Ctrl+N, Ctrl+T, Ctrl+W, Alt+Tab, Alt+F4, Win+L, Win+D). On capture, if the chosen combo matches, show a non-blocking warning row inside the editor: "Ctrl+C is commonly reserved for Copy. Using this combo will override the system default." Allow proceed. No modal interrupt.