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/infrastructure/src/lib/mongo/read-model.schemas.ts

@@ -8,6 +8,7 @@ import {
   ProjectReadModel,
   ReleaseReadModel,
   SavedFilterReadModel,
+  SprintReadModel,
   implicitRank,
 } from '@task-stream/api/tracker/domain';
 import { Schema } from 'mongoose';
@@ -24,6 +25,7 @@ export type IssueDoc = Doc<Omit<IssueReadModel, 'links'>> & {
 };
 export type CommentDoc = Doc<CommentReadModel>;
 export type ReleaseDoc = Doc<ReleaseReadModel>;
+export type SprintDoc = Doc<SprintReadModel>;
 export type ActivityDoc = Doc<ActivityReadModel>;
 export type TimelineDoc = Doc<IssueTimelineEntry>;
 export type NotificationDoc = Doc<NotificationReadModel>;
@@ -43,6 +45,7 @@ export const ReadModels = {
   Notification: 'NotificationReadModel',
   NotificationSettings: 'NotificationSettings',
   SavedFilter: 'SavedFilter',
+  Sprint: 'SprintReadModel',
 } as const;
 
 const userRef = { _id: false, id: String, name: String };
@@ -79,6 +82,7 @@ export const IssueSchema = new Schema<IssueDoc>(
     reporter: userRef,
     assignee: userRef,
     release: { _id: false, id: String, name: String },
+    sprint: { _id: false, id: String, name: String },
     outwardLinks: [link],
     inwardLinks: [link],
     watchers: [userRef],
@@ -108,6 +112,7 @@ IssueSchema.index({ 'watchers.id': 1 });
 IssueSchema.index({ 'parent.id': 1 });
 IssueSchema.index({ projectId: 1, rank: 1 });
 IssueSchema.index({ 'release.id': 1 });
+IssueSchema.index({ 'sprint.id': 1 });
 IssueSchema.index({ title: 'text', description: 'text', key: 'text' });
 
 export const CommentSchema = new Schema<CommentDoc>(
@@ -126,6 +131,16 @@ export const ReleaseSchema = new Schema<ReleaseDoc>(
   { ...loose, collection: 'releases_view' },
 );
 
+export const SprintSchema = new Schema<SprintDoc>(
+  {
+    _id: String,
+    projectId: { type: String, index: true },
+    status: String,
+    version: Number,
+  },
+  { ...loose, collection: 'sprints_view' },
+);
+
 export const ActivitySchema = new Schema<ActivityDoc>(
   {
     _id: String,
@@ -182,6 +197,7 @@ export const READ_MODEL_SCHEMAS = [
   { name: ReadModels.Issue, schema: IssueSchema },
   { name: ReadModels.Comment, schema: CommentSchema },
   { name: ReadModels.Release, schema: ReleaseSchema },
+  { name: ReadModels.Sprint, schema: SprintSchema },
   { name: ReadModels.Activity, schema: ActivitySchema },
   { name: ReadModels.Timeline, schema: TimelineSchema },
   { name: ReadModels.Notification, schema: NotificationSchema },
@@ -207,6 +223,7 @@ export function issueFromDoc(doc: IssueDoc): IssueReadModel {
     watchers: rest.watchers ?? [],
     parent: rest.parent?.id ? rest.parent : null,
     rank: rest.rank ?? implicitRank(rest.number),
+    sprint: rest.sprint?.id ? rest.sprint : null,
     checklist: rest.checklist ?? [],
   };
 }