Link views from the zone list, add breadcrumbs and view colours

The view shown in the zone list and on the zone page now links to that
view. The zone page and changeset page get breadcrumbs, and the zone list
keeps its filters in the address so going back restores them. Views can
be given a colour (Views > Edit, `jarl view color`, PUT /views/{id}/color)
so zones of the same view are easy to spot; the colour is UI-only, kept
outside changesets, and needs no deploy.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -14,6 +14,21 @@ All notable changes to Jarl are documented here. The format follows
   zone (`example.com` or `JARL_TEST_ZONE`) and a reverse zone, starts named
   and prints the steps to install Jarl and adopt the configuration
   (docs/development.md).
+- View colours. Give a view a colour (Views → Edit, `jarl view color`, or
+  `PUT /views/{id}/color`) and the zone list, the zone page and the views
+  list show its name in that colour. The colours are muted, and pastel in
+  dark mode. The default is the link colour. A colour isn't configuration,
+  so setting one needs no changeset or deploy.
+- Breadcrumbs on the zone page (Zones › view) and the changeset page
+  (History). The zone list keeps its filter, view and type in the address,
+  so going back to it, by breadcrumb or the browser's back button, restores
+  them.
+
+### Changed
+
+- The view in the zone list, and on the zone page, links to that view,
+  and the views page highlights it. It used to be plain text, and the zone
+  page linked to the views page as a whole.
 
 ### Fixed