Unused Ghostty FFI functions that could improve behavior

[mvbmir]

Summary

Several Ghostty FFI functions are declared in limux-ghostty-sys/src/lib.rs but never called. Some could improve limux behavior.

Unused FFI Functions

Function	Potential Use
ghostty_app_free	Proper cleanup on app exit (currently leaks)
ghostty_app_set_focus	Explicitly tell Ghostty when the app gains/loses focus (may fix edge cases with unfocused terminals still processing input)
ghostty_surface_refresh	Force a surface redraw without waiting for the next render cycle
ghostty_surface_request_close	Clean surface shutdown instead of just dropping the widget
ghostty_surface_size	Query actual surface dimensions (useful for control bridge introspection)

Priority

• ghostty_surface_request_close and ghostty_app_free are the most impactful for correctness
• ghostty_surface_size would be useful for the pane/surface bridge commands (Expose pane/surface commands in control bridge #10)