fusion: fix memory corruption in single-app mode
        (fusion ref was already destroyed after execution completed)
libfusion: Add fusion_fd() and fusion_dispatch() to allow integration into main loop
Core: Don't freeze when moving layer (update_primary_region_config)
Core: Fix stereo updates (don't dispatch from layer function)
libfusion: Set fd to non-blocking in fusion_stop_dispatcher
libfusion: Fix single app build
Core: Shutdown fixes