[keithcurtis1]

Summary

• Added a Slide Show button (next to Set as Grid/Scene) that sets the current scene live, then cycles every image in the scene through the backdrop slot on a timed loop, crossfading between them the same way a manual backdrop click does. The button's icon switches from a play triangle to a stop square while running.
• New Settings control, Slide Interval, sets how long each image holds before crossfading to the next (default 10 seconds).
• While cycling, only the caption updates with each image — star highlights and audio track switching are held until the loop actually stops (button clicked again, an image clicked to set it as backdrop, Set Scene, Set Grid, or Wipe the Scene), then applied once to whichever image is showing, the same as a normal click.
• The loop pauses on its own whenever no player or GM is actually viewing the stage page, and resumes once someone is. Does nothing if the scene has fewer than two images.
• Fixed: making a backup didn't refresh the interface, so a brand-new backup wouldn't show up as a Restore option until something else happened to redraw the handout.