NodeList.prototype.forEach was added in Safari 10 / iOS 10.
On iOS 9 it throws 'TypeError: forEach is not a function' at
init time, before connect() is called — leaving the app stuck
on 'Nicht verbunden' despite the async/await fix.

Added qsa(selector, root?) helper that wraps querySelectorAll
in Array.prototype.slice.call() to produce a real Array, then
replaced all three call sites:
  - document.querySelectorAll('.btn-seek').forEach
  - starEls (stored NodeList).forEach  x2
  - playlistList.querySelectorAll('li').forEach

Array.prototype.forEach has been safe since iOS 4.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>