Potential experiments

perf(app): load sheet and popout media against their own scrollers (#1900)

fix(app): only track hover on reactions that have an animated emoji (#1899)

fix(app): stop pickers re-slicing their grid on first paint (#1898)

fix(app): stop rewriting message emoji urls to toggle animation (#1897)

fix(app): stop rewriting message emoji urls to toggle animation

perf(app): show the message action bar from css not remounting (#1896)

perf(app): render member list rows in scroll chunks (#1895)

fix(app): stop the inbox reshuffling unread channels as you read them (#1894)

perf(app): defer video embed metadata probes until hover (#1893)

fix(app): keep animated embed images animated (#1892)

fix(app): fade image embed placeholders out instead of images in (#1891)

feat(app): suggest recent speakers and stop autocomplete list flicker (#1890)

fix(app): label pending composer attachments for screen readers (#1889)

fix(app): request attachment images at their real mosaic tile size (#1888)

feat(app): render search filters as inline tokens you can type through (#1887)

feat(app): keep search history per conversation and allow in: in DMs (#1886)

feat(app): keep search history per conversation and allow in: in DMs

fix(app): open channels at the unread divider and settle jump scrolling (#1885)

fix(api): distinguish a deleted reply target from no reply (#1884)

fix(app): animate reaction emoji only while hovering them (#1883)