feat(sprints): interface de création et gestion des sprints (frontend)

Ticket #11 — surface UI de gestion des sprints (frontend pur).

- Nouveau composant SprintManager : création (nom optionnel), édition et
  gestion du cycle de vie d'un sprint, contrôles accessibles (pas de DnD).
- useTickets étendu aux opérations de gestion de sprint ; ports, adaptateurs
  (ticket.ts, mock/index.ts) et TicketsPanel câblés en conséquence.
- Tests Vitest associés (tickets.test.tsx).

Typecheck / vitest (497+ tests) / build verts.

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

frontend/src/features/tickets/useTickets.ts

@@ -40,6 +40,20 @@ export interface TicketsViewModel {
    * version column. Refreshes on the resulting `issueSprintChanged` event.
    */
   assignSprint: (ref: string, sprintId: string | null) => Promise<boolean>;
+  /** Creates a sprint (#11). Returns the created sprint, or `null` on error. */
+  createSprint: (name: string) => Promise<Sprint | null>;
+  /** Renames a sprint using its current version (#11). */
+  renameSprint: (sprintId: string, name: string) => Promise<boolean>;
+  /**
+   * Moves a sprint one slot up/down in execution order via `reorderSprints`
+   * (#11). A no-op at the ends. Accessible (button-driven), non-DnD.
+   */
+  moveSprint: (sprintId: string, direction: "up" | "down") => Promise<boolean>;
+  /**
+   * Deletes a sprint (#11). The backend unassigns its tickets (does NOT delete
+   * them). Refreshes both the sprint list and the tickets.
+   */
+  deleteSprint: (sprintId: string) => Promise<boolean>;
 }
 
 function describe(e: unknown): string {
@@ -116,6 +130,80 @@ export function useTickets(projectId: string): TicketsViewModel {
     [projectId, ticket, refresh, refreshSprints],
   );
 
+  const createSprint = useCallback(
+    async (name: string): Promise<Sprint | null> => {
+      setError(null);
+      try {
+        const created = await ticket.createSprint(projectId, name);
+        await refreshSprints();
+        return created;
+      } catch (e) {
+        setError(describe(e));
+        return null;
+      }
+    },
+    [projectId, ticket, refreshSprints],
+  );
+
+  const renameSprint = useCallback(
+    async (sprintId: string, name: string): Promise<boolean> => {
+      setError(null);
+      try {
+        const current = sprints.find((s) => s.id === sprintId);
+        if (!current) return false;
+        await ticket.renameSprint(projectId, sprintId, name, current.version);
+        await refreshSprints();
+        return true;
+      } catch (e) {
+        setError(describe(e));
+        return false;
+      }
+    },
+    [projectId, ticket, sprints, refreshSprints],
+  );
+
+  const moveSprint = useCallback(
+    async (sprintId: string, direction: "up" | "down"): Promise<boolean> => {
+      setError(null);
+      const ordered = [...sprints].sort((a, b) => a.order - b.order);
+      const index = ordered.findIndex((s) => s.id === sprintId);
+      const swapWith = direction === "up" ? index - 1 : index + 1;
+      if (index === -1 || swapWith < 0 || swapWith >= ordered.length) {
+        return false;
+      }
+      const next = [...ordered];
+      [next[index], next[swapWith]] = [next[swapWith], next[index]];
+      try {
+        await ticket.reorderSprints(
+          projectId,
+          next.map((s) => s.id),
+        );
+        await refreshSprints();
+        return true;
+      } catch (e) {
+        setError(describe(e));
+        return false;
+      }
+    },
+    [projectId, ticket, sprints, refreshSprints],
+  );
+
+  const deleteSprint = useCallback(
+    async (sprintId: string): Promise<boolean> => {
+      setError(null);
+      try {
+        await ticket.deleteSprint(projectId, sprintId);
+        // Delete unassigns tickets → refresh both projections.
+        await Promise.all([refresh(), refreshSprints()]);
+        return true;
+      } catch (e) {
+        setError(describe(e));
+        return false;
+      }
+    },
+    [projectId, ticket, refresh, refreshSprints],
+  );
+
   useEffect(() => {
     void refresh();
   }, [refresh]);
@@ -157,5 +245,9 @@ export function useTickets(projectId: string): TicketsViewModel {
     refresh,
     create,
     assignSprint,
+    createSprint,
+    renameSprint,
+    moveSprint,
+    deleteSprint,
   };
 }