Weather rows play at the timeline's speed; the frame time shows under reduced motion; tidy the timeline's mark label

A weather row's play ran the world clock at whatever rate it had, and
going live set that back to 1, so the speed chosen on the timeline was
lost. The world clock now keeps its rate while paused and live, and the
timeline's speed sets it whenever it is chosen, so any play runs at it.
A row's play starts from the start of the covered time when live or at
its end, as the timeline's does, and does nothing while every product the
row shows is suspended, as its reduced-motion note says.

Live, the Weather panel's frame time is the newest of each product's
frames, suspended or not, so it no longer goes away under reduced motion,
on a hidden page or without an imagery host.

A weather layer made without a weather clock builds its own when first
enabled rather than when made, so a layer never turned on leaves the
world clock alone, and its own clock (createWeatherClock({ shared: false }))
leaves the world's time where it is when destroyed; only the last shared
weather clock sends the world live.

On the timeline, a zoom or a pan clears the hovered tick's label, a label
is never wider than the track and ends in an ellipsis, and a mark's label
is cut to 60 characters (WORLD_CLOCK_MARK_LABEL_LENGTH).

The changelog entry says what a row's step does, names the earthquake
layer's new exports and says it registers with the world clock.

docs/APPLICATION.md

@@ -199,8 +199,8 @@ the unregister; call `worldClock.coverageChanged()` when that time changes.
 `{ start, end, marks? }` in epoch ms. `marks` are the moments worth going to,
 drawn as ticks the timeline's arrow keys step to and a tap on or within 6 px of
 snaps to. Each mark is a number, or `{ time, label?, id?, kind? }`: `label` is
-short text shown when the pointer is on the tick and told with the time while
-the handle is on the mark, `id` the layer's own key for the event and `kind`
+short text (cut to 60 characters, ending in `…`) shown when the pointer is on
+the tick and told with the time while the handle is on the mark, `id` the layer's own key for the event and `kind`
 what sort of event it is (`'launch'`, `'earthquake'`). The two forms may be
 mixed; a mark without a finite time, and a `label`, `id` or `kind` that is not
 a non-empty string, are ignored. `worldClock.coverage()` returns the union of

docs/CURRENT-STATE.md

@@ -8545,7 +8545,9 @@ that timeline but are not marks on it: the timeline marks only events (launches,
 and earthquakes of magnitude 6 and up while that layer is on), so its arrow keys
 step to those, or along the track where there are none. A mark may carry a
 label (a launch's mission name, cut to 27 characters in capitals as the mission
-index shows names; an earthquake's magnitude and place). The pointer within
+index shows names; an earthquake's magnitude and place) of up to 60 characters;
+a longer one ends in `…`, and a label is never wider than the track. A zoom or
+a pan clears a hovered label. The pointer within
 6 px of a tick shows its label over the track, and a tap there goes to the
 mark's time exactly; a tap elsewhere goes to the time under it and a drag
 scrubs. With the handle on a mark, its label follows the time in the handle's
@@ -8570,14 +8572,21 @@ every frame shows. Hidden documents, reduced motion and unavailable imagery
 hosts suspend products. Re-enabling or
 restoring a host joins the retained history target. The wind row explicitly says
 “Forecast · does not follow history” while the observed clock is in history mode.
-The Weather panel's frame time shows the newest frame and its age while live,
-and the timeline time alone at a past time.
+The Weather panel's frame time shows the newest frame and its age while live
+(each product's newest, suspended products included), and the timeline time
+alone at a past time.
 The catalog exposes `weatherClock` and destroys it with its lifetime signal. It
 has no time controls of its own: `weatherClock.world` is the world clock it
 follows, where time moves. A weather row's `play`, `latest` and `step` params
-move that world clock as the timeline does. A weather layer built without a shared
-clock keeps one of its own on the page's world clock for its lifetime; it has
-no frame replay of its own either way.
+move that world clock as the timeline does: `play` runs at the speed chosen on
+the timeline (the world clock keeps its rate while paused and live), from the
+start of the covered time when live or at its end, and does nothing while
+every product the row shows is suspended. A weather layer built without a
+shared clock builds one of its own on the page's world clock when first
+enabled (`createWeatherClock({ shared: false })`) and keeps it for its
+lifetime; destroying it leaves the world's time where it is, and only the last
+shared weather clock destroyed sends the world live. Neither has a frame replay
+of its own.
 
 Source, opacity and coverage navigation live in the WEATHER panel's cards, not
 in the rows; the panel shows the frame time and has no time controls. The