feat: estimate tickets and see the team's velocity

Story points can be set on the ticket page and when creating a ticket,
and show on cards, column headers, subtasks and the backlog. The Sprints
tab charts the points finished per closed sprint and warns when a planned
sprint holds more than the recent average.

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

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

@@ -6,3 +6,4 @@ export * from './lib/ports/gateways';
 export * from './lib/models/mentions';
 export * from './lib/models/hierarchy';
 export * from './lib/models/views';
+export * from './lib/models/estimation';