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/web/tracker/infrastructure/src/lib/tracker-infrastructure.providers.ts

@@ -11,6 +11,7 @@ import {
   ProjectsGateway,
   ReleasesGateway,
   SavedFiltersGateway,
+  SprintsGateway,
   TrackerRealtimeGateway,
   UsersGateway,
 } from '@task-stream/web/tracker/domain';
@@ -26,6 +27,7 @@ import { HttpAttachmentsGateway } from './adapters/http-attachments.gateway';
 import { GraphqlProjectsGateway } from './adapters/graphql-projects.gateway';
 import { GraphqlRealtimeGateway } from './adapters/graphql-realtime.gateway';
 import { GraphqlSavedFiltersGateway } from './adapters/graphql-saved-filters.gateway';
+import { GraphqlSprintsGateway } from './adapters/graphql-sprints.gateway';
 
 /** Ports → GraphQL adapters (and REST for files). */
 export function provideTrackerInfrastructure(): EnvironmentProviders {
@@ -40,5 +42,6 @@ export function provideTrackerInfrastructure(): EnvironmentProviders {
     { provide: NotificationsGateway, useClass: GraphqlNotificationsGateway },
     { provide: TrackerRealtimeGateway, useClass: GraphqlRealtimeGateway },
     { provide: SavedFiltersGateway, useClass: GraphqlSavedFiltersGateway },
+    { provide: SprintsGateway, useClass: GraphqlSprintsGateway },
   ]);
 }