Show an ongoing notification while the app is working

Everything this app asks for is minutes of the build machine's time
followed by a download, and all of it runs in the list screen's own
coroutines -- so with the app in the background the process is an
ordinary cached one, and Android is free to take it away halfway
through a build. A foreground service is the only way to say otherwise,
and its notification is both what that costs and what it is for: the
work is visible from the shade while it runs, and one tap comes back to
the card that started it.

The work itself stays where it is. WorkNoticeService runs nothing --
it collects a list of what is happening and reposts one notification,
stopping as soon as the list is empty -- and that list is *derived* by
workItems from the same projectStates/componentStates the cards are
drawn from, so there is nothing to forget to post and nothing to forget
to take back. The words are shared rather than written twice:
componentWorkLine and buildLine are now read by the card's own bars and
by the notification alike.

Measured on API 36 rather than assumed: the collapsed row drops the
content text the moment there is a progress bar, so one thing running
puts both the component and what is happening to it in the title
("Test Tablet / tablet: building  14/30"); several get a line each in
the expanded view and an indeterminate bar, there being no honest
single number for two builds at once. With the app at the home screen
the process sits at fg-service-act rather than cached, and the builds
it started landed while it was there.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -123,6 +123,15 @@ Better still, let the project carry that itself — see [below](#letting-a-proje
 Set `gitPull: false` on a checkout that should never be moved from a
 phone. Paths accept `~`, and are shown that way.
 
+While anything is building, downloading or installing, the app keeps an
+ongoing notification saying what is running and how far along it is — one
+line per component, with each build's own count where the command reports
+one. It is there to be watched, and it is also what keeps the work alive:
+without it the app is an ordinary backgrounded process, and Android is
+free to reclaim it partway through a build. It goes away by itself when
+the last thing finishes. Refusing the notification permission costs the
+watching and not the work.
+
 ### Updating this server itself
 
 The **Dev Updater** card pulls and builds like any other, and is