Onboarding · Help: articles in a list the keyboard walks, a long address cut

HelpPanel lists its articles in lists::SelectableList: the list is one
stop whose cursor scrolls into view, and Enter or a double press opens
an article, focus going to All articles as before. SelectableList now
activates on Enter's release, armed by its own press, as the palette
and menus pick: an activation that moves focus left the release to
press what took it, here the way back. ContactSupport cuts a long
address in the middle and puts a Copy beside it. The lists tests move
into a folder, the release tests on their own.

examples/gallery/pages/onboarding/mod.rs

@@ -30,6 +30,7 @@ const SCRIPT: &[Step] = &[
     Step::Key("escape"),
     Step::DownAt("onboarding-help-panel", 120.0, 124.0),
     Step::UpAt("onboarding-help-panel", 120.0, 124.0),
+    Step::Key("enter"),
     Step::Wait(200),
     Step::Shot("help-article"),
     Step::DownAt("onboarding-shortcuts", 20.0, 16.0),