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/domain/src/lib/models/models.ts

@@ -4,6 +4,7 @@ import {
   IssuePriority,
   ProjectRole,
   ReleaseStatus,
+  SprintStatus,
   StatusCategory,
 } from './enums';
 import { ProjectSettings } from './workflow';
@@ -107,6 +108,7 @@ export interface IssueSummary {
   priority: IssuePriority;
   assignee: UserRef | null;
   release: { id: string; name: string } | null;
+  sprint: { id: string; name: string } | null;
   labels: string[];
   /** The epic or ticket this one breaks down. */
   parent: IssueParent | null;
@@ -159,6 +161,40 @@ export interface Comment {
   editedAt: string | null;
 }
 
+export interface SprintProgress {
+  total: number;
+  /** Done or cancelled. */
+  finished: number;
+  percent: number;
+  storyPoints: number;
+  finishedStoryPoints: number;
+}
+
+/** A time-boxed iteration of a project. */
+export interface Sprint {
+  id: string;
+  projectId: string;
+  name: string;
+  goal: string | null;
+  /** `YYYY-MM-DD`, both included. */
+  startDate: string;
+  endDate: string;
+  status: SprintStatus;
+  startedAt: string | null;
+  closedAt: string | null;
+  progress: SprintProgress;
+}
+
+/** Per day of a sprint; null for the days to come. */
+export interface SprintBurndown {
+  sprintId: string;
+  dates: string[];
+  scope: (number | null)[];
+  remaining: (number | null)[];
+  remainingPoints: (number | null)[];
+  ideal: number[];
+}
+
 export interface Release {
   id: string;
   projectId: string;