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/application/src/lib/commands/command-handlers.ts

@@ -30,6 +30,7 @@ import { DetachFileCommandHandler } from './detach-file.command-handler';
 import { WatchIssueCommandHandler } from './watch-issue.command-handler';
 import { SetIssueParentCommandHandler } from './set-issue-parent.command-handler';
 import { RankIssueCommandHandler } from './rank-issue.command-handler';
+import { SPRINT_COMMAND_HANDLERS } from './sprint.command-handlers';
 import { DetachFromParentCommandHandler } from './detach-from-parent.command-handler';
 import {
   AddChecklistItemCommandHandler,
@@ -71,6 +72,7 @@ export const COMMAND_HANDLERS = [
   WatchIssueCommandHandler,
   SetIssueParentCommandHandler,
   RankIssueCommandHandler,
+  ...SPRINT_COMMAND_HANDLERS,
   AddChecklistItemCommandHandler,
   UpdateChecklistItemCommandHandler,
   RemoveChecklistItemCommandHandler,