Clean up show notes embedded web view

After the full screen player is open, the show notes have been viewed and then the full screen player is closed the web view isn't cleaned up. This is because the full screen player is still peeking to show the mini player.

It would be good to clean up the web view earlier as we often see it in the Application Exit support logs and might be causing us other issues.

Trace the full-screen player and show-notes web view lifecycle, then reproduce the sequence of opening the player, viewing show notes, closing the player, and leaving the mini player peeking. Done means the web view is cleaned up earlier in this sequence and no longer appears in Application Exit support logs.

Written by the indexing model from the issue text.