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/graphql/fragments.graphql

@@ -69,6 +69,10 @@ fragment IssueSummaryFields on Issue {
     id
     name
   }
+  sprint {
+    id
+    name
+  }
   parent {
     id
     key

libs/web/tracker/infrastructure/src/lib/graphql/issues.graphql

@@ -8,6 +8,7 @@ query Board(
   $labels: [String!]
   $search: String
   $unassigned: Boolean
+  $sprintId: ID
 ) {
   project(idOrKey: $idOrKey) {
     id
@@ -20,6 +21,7 @@ query Board(
       labels: $labels
       search: $search
       unassigned: $unassigned
+      sprintId: $sprintId
       perColumn: 100
     ) {
       status

libs/web/tracker/infrastructure/src/lib/graphql/sprints.graphql

@@ -0,0 +1,81 @@
+fragment SprintFields on Sprint {
+  id
+  projectId
+  name
+  goal
+  startDate
+  endDate
+  status
+  startedAt
+  closedAt
+  progress {
+    total
+    finished
+    percent
+    storyPoints
+    finishedStoryPoints
+  }
+}
+
+query Sprints($projectId: ID!) {
+  sprints(projectId: $projectId) {
+    ...SprintFields
+  }
+}
+
+query SprintBurndown($id: ID!) {
+  sprint(id: $id) {
+    id
+    burndown {
+      sprintId
+      dates
+      scope
+      remaining
+      remainingPoints
+      ideal
+    }
+  }
+}
+
+mutation CreateSprint($input: CreateSprintInput!) {
+  createSprint(input: $input) {
+    ...CommandResultFields
+  }
+}
+
+mutation UpdateSprint($input: UpdateSprintInput!) {
+  updateSprint(input: $input) {
+    ...CommandResultFields
+  }
+}
+
+mutation StartSprint($sprintId: ID!) {
+  startSprint(sprintId: $sprintId) {
+    ...CommandResultFields
+  }
+}
+
+mutation CloseSprint($sprintId: ID!, $carryOverToSprintId: ID) {
+  closeSprint(sprintId: $sprintId, carryOverToSprintId: $carryOverToSprintId) {
+    ...CommandResultFields
+  }
+}
+
+mutation DeleteSprint($sprintId: ID!) {
+  deleteSprint(sprintId: $sprintId) {
+    ...CommandResultFields
+  }
+}
+
+mutation SetIssueSprint($issueId: ID!, $sprintId: ID) {
+  setIssueSprint(issueId: $issueId, sprintId: $sprintId) {
+    ...CommandResultFields
+  }
+}
+
+subscription SprintChanged($projectId: ID!) {
+  sprintChanged(projectId: $projectId) {
+    action
+    sprintId
+  }
+}