Summary

• Add URL query parameter support to the sandbox for easier testing:
  • ?src=vimeo|youtube|hls|video|audio|live|dash - select source
  • ?autoplay - enable autoplay
  • ?muted - start muted
• Log auto-play and auto-play-fail events to console

Why add this?

This helps testing (and thus developing) features such as autoplay. I need that to make another issue apparent, for which I'll create a PR shortly. If interested, see its' description below.

Known Issue - Vimeo Autoplay Muted State

This PR also makes a bug in the Vimeo provider visible: when a video starts with autoplay, it may be muted by the browser (due to Chrome's autoplay policy), yet the player UI shows it as unmuted.

Repro: Visit http://localhost:3100/sandbox/index.html?src=vimeo&autoplay

Issue: Vidstack's onAutoPlay event reports muted: false even when Chrome forces the Vimeo iframe to mute due to autoplay policy.

Root cause: For Vimeo iframe embeds, Chrome's autoplay policy applies inside the iframe and Vimeo handles muting internally. Vidstack reports its own requested state (muted: false, volume: 1), not what Vimeo actually did.

Expected behavior: Either:

1. Vidstack should detect Vimeo's actual muted state (if possible)
2. Document this limitation in the autoplay docs
3. Provide a way to detect "autoplay succeeded but with silent audio"