* test(player): measure heavy films in real Safari and Chrome on macOS
* test(player): count runtime media seeks and rate writes during the Safari bench
* test(player): compare the Safari bench against native playback of the same media
* test(player): split Safari control playback into per-frame media writes and per-frame transforms
* perf(core): write media volume and mute only when they change
* test(player): presented frame rate and compositor-animation controls in the Safari bench
* perf(core): keep the media volume guard without a new comment line
* test(player): derive presented frames from playback counters and snapshot video state
* test(player): control page plays only listed media, and anchor the Safari process match
* test(player): send the bench as code, and write only validated numbers from the browser
* fix(player): perf host page gives the player a real box, so films are on screen when measured
* fix(player): a player with no height set takes its film's shape instead of collapsing to nothing
The player box had no intrinsic height, so an embed that set only a width (or nothing) was 0 px tall
and showed no picture. An in-flow sizer now carries the composition's aspect ratio; a height the
embed sets still wins, and a height-only embed keeps its full width.
* test(player): label each embed on the player box page
