feat(sprints): surface frontend du modèle de sprints

Ticket #10 — volet frontend des sprints.

- Domaine et ports frontend étendus au modèle de sprints (domain/index.ts,
  ports/index.ts).
- Adaptateurs : ticket.ts et mock/index.ts câblent les opérations sprints.
- UI tickets : useTickets + TicketsPanel exposent le rattachement/gestion des
  sprints, avec tests Vitest associés.

Typecheck / vitest / build verts.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/domain/index.ts

@@ -165,6 +165,28 @@ export type DomainEvent =
       agentId: string;
       version: number;
     }
+  | {
+      /**
+       * A ticket changed sprint membership (ticket #10). Mirror of the backend
+       * `DomainEventDto::IssueSprintChanged`. `from`/`to` are sprint ids (`null`
+       * ⇒ no sprint). Starts with `issue`, so {@link isTicketEvent} matches it
+       * and ticket lists refresh automatically.
+       */
+      type: "issueSprintChanged";
+      issueRef: string;
+      from: string | null;
+      to: string | null;
+      version: number;
+    }
+  | { type: "sprintCreated"; sprintId: string; order: number }
+  | { type: "sprintRenamed"; sprintId: string; name: string; version: number }
+  | {
+      type: "sprintReordered";
+      sprintId: string;
+      order: number;
+      version: number;
+    }
+  | { type: "sprintDeleted"; sprintId: string }
   | {
       /**
        * An intermediate assistant announcement emitted **during** an inter-agent
@@ -197,6 +219,17 @@ export function isTicketEvent(
   return event.type.startsWith("issue");
 }
 
+/**
+ * Whether a domain event is a sprint lifecycle event (`sprint*`). Lets the
+ * ticket view-model re-fetch the sprint list when sprints are created, renamed,
+ * reordered or deleted (ticket #10).
+ */
+export function isSprintEvent(
+  event: DomainEvent,
+): event is Extract<DomainEvent, { type: `sprint${string}` }> {
+  return event.type.startsWith("sprint");
+}
+
 /** Where a project physically lives (mirror of the backend `RemoteRef`). */
 export type RemoteRef =
   | { kind: "local" }
@@ -865,6 +898,22 @@ export interface TicketLink {
   kind: TicketLinkKind;
 }
 
+/** Lifecycle status of a sprint (mirror of the backend `SprintStatus`). */
+export type SprintStatus = "planned" | "active" | "done";
+
+/** A sprint bucket tickets can belong to (mirror of `SprintDto`). */
+export interface Sprint {
+  id: string;
+  /** Reorderable position; sections are displayed by ascending `order`. */
+  order: number;
+  name: string;
+  status: SprintStatus;
+  /** How many tickets currently belong to this sprint. */
+  ticketCount: number;
+  /** Optimistic-concurrency version. */
+  version: number;
+}
+
 /** The full ticket, as returned by `ticket_read`/`ticket_create`/… . */
 export interface Ticket {
   id: string;
@@ -874,6 +923,8 @@ export interface Ticket {
   description: string;
   status: TicketStatus;
   priority: TicketPriority;
+  /** Sprint membership (`null` ⇒ no sprint). Additive (ticket #10). */
+  sprintId?: string | null;
   /** Present only when the ticket was read with `includeCarnet`. */
   carnet?: string;
   links: TicketLink[];
@@ -893,6 +944,8 @@ export interface TicketSummary {
   title: string;
   status: TicketStatus;
   priority: TicketPriority;
+  /** Sprint membership (`null` ⇒ no sprint). Additive (ticket #10). */
+  sprintId?: string | null;
   assignedAgentIds: string[];
   updatedAt: number;
 }