feat: sprints with burndown and carry-over

Plan sprints with dates and a goal, run one at a time per project, and
put tickets in them from the ticket page. The Sprints tab follows the one
under way with its progress and a burndown in tickets or points against
the ideal line. Closing a sprint sends what was left to the next one or
back to the backlog; the board can be filtered by sprint.

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

libs/api/tracker/presenters/src/lib/graphql/enums.ts

@@ -6,6 +6,7 @@ import {
   NotificationKind,
   ProjectRole,
   ReleaseStatus,
+  SprintStatus,
   StatusCategory,
 } from '@task-stream/api/tracker/domain';
 
@@ -23,6 +24,10 @@ registerEnumType(StatusCategory, {
 registerEnumType(IssueLinkType, { name: 'IssueLinkType' });
 registerEnumType(ProjectRole, { name: 'ProjectRole' });
 registerEnumType(ReleaseStatus, { name: 'ReleaseStatus' });
+registerEnumType(SprintStatus, {
+  name: 'SprintStatus',
+  description: 'PLANNED, ACTIVE (one per project at a time) or CLOSED',
+});
 registerEnumType(LinkDirection, { name: 'LinkDirection' });
 registerEnumType(IssueSort, {
   name: 'IssueSort',