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>

libs/web/tracker/application/src/index.ts

@@ -7,3 +7,4 @@ export * from './lib/facades/home.facade';
 export * from './lib/facades/explore.facade';
 export * from './lib/facades/inbox.facade';
 export * from './lib/facades/epics.facade';
+export * from './lib/facades/backlog.facade';