Show a timer in the day bar while a walk is on

The bar already carries the asleep/awake counter; a walk in progress had
nothing, so "how long have we been out" meant going to the Walks panel to look.
It gets a second pill now, counting from the walk's start, and tapping it ends
the walk — the same bargain the sleep pill offers for the sleep boundary.

Two timers no longer fit beside the day controls on a narrow phone, so the bar
wraps. That needed the children grouping first: with seven loose ones the break
could land anywhere, and stranding "Today" alone on a second line is worse than
not wrapping at all. The timers are one group and the day controls another, so
the wrap falls between them.

Two things follow from the bar changing height. The tab bar sticks to that
height, and the ResizeObserver added when the pill first appearing had the same
effect already covers it — nothing new needed. And both pills go to standby
together while the big card is on screen: standby is visibility, not display,
so the bar keeps its wrapped height while you scroll and the tab bar beneath it
does not shuffle.

The card shows the walk while there is one. It has room for a single timer, and
you are necessarily awake on a walk, so "awake for 3h" is the less useful of the
two readings; the bar keeps both. That also meant moving the card out of the
early return for "no sleep logged yet" — a walk can be the first thing ever
recorded, and the card was staying blank through it.

src/changelog.json

@@ -1,4 +1,5 @@
 [
+  { "date": "2026-09-08", "text": "A walk in progress now has a timer in the frozen bar at the top, next to the asleep/awake one, counting from when the walk started — so you can see how long you have been out from any tab without going to look. Tapping it ends the walk, the same way tapping the sleep timer logs the sleep boundary. On a narrow phone two timers no longer fit beside the date controls, so the bar splits onto two rows while a walk is on and goes back to one when it ends. The big timer card on Today shows the walk too while there is one — you are awake on a walk either way, so the walk is the more useful of the two" },
   { "date": "2026-09-07", "text": "Going back to the Today tab no longer jumps the viewport either — by tapping it or with the back button. The other tabs stopped jumping in the last change, but returning to Today is a history step, and the browser was restoring the scroll position from when you last left it" },
   { "date": "2026-09-07", "text": "The tab row now matches the frozen row above it that holds the date. It was a different shade, and the two sat as separate bars with the date row's rounded corners cutting between them; they share the same card colour now, and once you have scrolled the log buttons away they join into a single rounded block instead of two stacked ones" },
   { "date": "2026-09-07", "text": "Switching tabs no longer jumps the page back to the top. The tab row is frozen to the top of the screen, so you change tabs from wherever you have scrolled to, and being thrown back past the log buttons you had just scrolled off was more disruptive than landing part-way down the new tab" },