feat: an ordered backlog

A Backlog tab lists the tickets still to start in the order the team will
take them; drag them, or use the arrows, to reorder. Moving a ticket only
rewrites that ticket's rank, read from the event store, and board columns
follow the same order.

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

apps/web/src/app/app.routes.spec.ts

@@ -28,6 +28,7 @@ describe('appRoutes', () => {
       '',
       'board',
       'issues/:issueKey',
+      'backlog',
       'epics',
       'releases',
       'dashboard',