Function next_render_phase 

pub fn next_render_phase(
    current: RenderPhase,
    event: RenderEvent,
) -> RenderPhase

Pure render-phase transition table, the analogue of frust-render’s next_phase. Total by design:

• SurfaceCreated → Active (create or recreate),
• SurfaceDestroyed → NoSurface,
• SurfaceChanged → the current phase unchanged (a resize never changes whether we can render — mirrors “resize stays Ready”),
• Pause → Paused unless there is no surface (you cannot pause what was never created),
• Resume → Active unless there is no surface (you cannot resume onto a surface that is gone; the shell must recreate it first via SurfaceCreated).