feat(playback): stream-info popover in the player overlay (#1578)

.changes/player-stream-info-popover.md

@@ -0,0 +1,11 @@
+---
+type: feature
+area: playback
+highlight: See what a stream really is while it plays
+---
+
+The player overlay now shows stream information: resolution, playback and source
+frame rates, stream and codec bitrates, audio details, buffer and dropped frames.
+Available in built-in web players and experimental frame-copy Embedded MPV.
+Unknown or unavailable values stay hidden; measured frame rates reflect dropped frames and
+stalls.