fix(anki): hold playback paused while media timing review is open

- Defer overlay resume requests (popup closed, hover left) during an active review and apply them when the review closes
- Add deferPlaybackResume to the media timing review runtime and gate sendRendererMpvCommand on it
- Document the paused-playback behavior and add a changelog fragment

changes/fix-timing-review-playback-hold.md

@@ -0,0 +1,4 @@
+type: fixed
+area: anki
+
+- Media timing review now keeps playback paused while it is open when the dictionary popup or subtitle hover pause ends, as with Hachidori popups closing when the review appears. Playback resumes after the review closes unless a dictionary popup is still open.