* test(player): play the WebKit audio edits in real Safari on a macOS runner
* fix(core): Safari keeps playing edits' audio without seeks or rate changes
* fix(core): keep the 0.1 s audio sync bound outside WebKit
* fix(core): restore main's audio steering outside WebKit
* fix(core): tell WebKit from the test DOM's user agent
* fix(core): name WebKit's audio start lag instead of commenting it
* fix(core): count embedded WKWebViews as WebKit for audio sync