Media · Audio and controls: player, waveform, spectrum, volume, speed, transport and playlist

AudioPlayer sets a song's cover, title and artist over a scrubber with
the time played and left, the transport and the volume. AudioWaveform
draws peaks gathered to the bars that fit, dark as far as it has played,
and seeks by press, drag and keys, with the time tip the scrubber shares.
AudioSpectrum shows levels by pitch. VolumeControl mutes from its speaker,
and moving its slider while muted unmutes. PlaybackSpeedControl picks from
a menu. MediaControls holds shuffle, back, play, forward and repeat.
Playlist builds on SelectableList: the song under way is lit with moving
bars, and Enter or a double press plays another.

The video player's bar now rests while the stage itself holds focus, a
key it takes wakes the bar, and a press on a resting bar only wakes it.

AGENTS.md

@@ -76,7 +76,7 @@ Ely GPUI Component. A component library for GPUI, in light and dark.
 - A dialog goes through `overlays::Dialog`: scrim, focus trap, Escape and focus return live there. AlertDialog, ConfirmDialog and PromptDialog build on it; a fullscreen dialog fills the window below its title bar. A dialog's card fits the window, a title bar's height clear at each end; its body scrolls and its actions stay.
 - Controls on a dark layer over pictures are `overlays::media_button`, light icons that dim when they have nowhere to go, for the lightbox and a video player's bar alike.
 - A component's letter keys step aside while Command or Control is held, so the app's shortcuts reach the app (`media::ImageAnnotator`, `VideoPlayer`, `VideoThumbnailStrip`).
-- A tip over a track splits the free width around it by the pointer's share: it stays inside the track and under the pointer, and nothing is measured (`media::Scrubber`).
+- A tip over a track splits the free width around it by the pointer's share: it stays inside the track and under the pointer, and nothing is measured (`media::scrubber::time_tip`, for the scrubber and the waveform).
 - `primitives::Severity` names info, success, warning and danger with their colors and icons, for alerts and feedback alike.
 - Rows that move are keyed. `motion::Flip` places them absolutely from last frame's heights, so no frame shows a row at its new place before it glides there, and drives the glide from elapsed time: an animation id that changes per move would rebuild the row's keyed state. `Reorder` holds a row by key, drags with an empty ghost and moves the held row itself.
 - A marker that slides between items (segment thumb, tab line) measures them with `motion::slide` and eases with `glide`.
@@ -126,6 +126,7 @@ Ely GPUI Component. A component library for GPUI, in light and dark.
 - A mode that leaves on Escape holds its own focus through `primitives::hold_focus`: turned on while focus is elsewhere, it takes focus so Escape reaches it, and `hand_back` returns it (`documents::ZenMode`, `collab::FollowMode`).
 - A chat holds at its newest message through gpui's `list` with `ListAlignment::Bottom`: it sticks while scrolled to the end, and `scroll_to` one past the last item sticks it again; that call sends no scroll event, so the owner clears its own away state (`chat::MessageList`).
 - Anything pressable is a Tab stop: a row, card or toggle takes `tab_index(0)` and `focus_ring`, with a 1px border that stays transparent where it shows none; gpui presses it on the release of Enter or Space.
+- A list of pressable rows goes through `lists::SelectableList`, whose cursor reaches them by key: Up and Down move, Enter or a double press activates (`media::Playlist`). A bare `ListItem` press is the pointer's only.
 - A row that holds text beside fixed parts lets the text give way: the text takes `flex_1().min_w_0()` and an `Ellipsis`; counts, icons, dates and chevrons take `flex_none`.
 - A mark over a text field reads the field at paint time, from a canvas laid over it (`collab::RemoteCursor`): by then `TextInput::bounds_for` holds this frame's layout, and a still page never renders again to catch up.
 - A callback field holds a named `type` alias; clippy's type_complexity rejects `Option<Rc<dyn Fn(..)>>`. A chapter shares one alias per shape.