v0.10.0

• Replace internal SlideChain with an exported SlideContext class. SlideContext accumulates elapsed time across after() calls exactly as SlideChain did, but also exposes find(), setTimeout(), and a get elapsed() getter. Slide#after() now returns a SlideContext — existing slide scripts are unaffected.
• Add Slide#loop(callback, {delay}) — runs a callback in a repeating loop until the slide changes. The callback receives a fresh SlideContext each iteration so it can schedule steps with after(). The loop waits for all steps to complete (context.elapsed) plus an optional extra delay before starting the next iteration. All timeouts flow through the slide's existing tracked setTimeout, so they are cancelled automatically on slide change.