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/presenters/src/lib/pages/board.page.scss

@@ -131,3 +131,8 @@
   outline-offset: -4px;
   border-radius: 0.625rem;
 }
+
+.ts-column__points {
+  font-weight: 400;
+  color: var(--ts-muted);
+}