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/api/tracker/domain/src/lib/events/index.ts

@@ -30,3 +30,4 @@ export * from './issue-parent-changed.event';
 export * from './issue-checklist-item-added.event';
 export * from './issue-checklist-item-updated.event';
 export * from './issue-checklist-item-removed.event';
+export * from './issue-ranked.event';