feat(tickets): surface frontend V1 du système de tickets

Surface UI complète des tickets (domaine Issue exposé « ticket »),
validée QA de bout en bout : cargo build + tests backend verts,
npm run build + npm test (459) verts.

- Domaine : DTO Ticket, 9 events Issue* + guard isTicketEvent.
- Ports : TicketGateway (+ types query/input) ajouté à Gateways.
- Adapters : TauriTicketGateway réel (+ isTicketVersionConflict),
  wiring, et MockTicketGateway pour les tests.
- Feature tickets : hooks (useTickets, useTicketDetail,
  useProjectAgents), TicketsPanel, TicketDetail, TicketsView,
  ticketMeta + tests.
- ProjectsView : onglet sidebar « Tickets ».

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

frontend/src/features/tickets/index.ts

@@ -0,0 +1,22 @@
+/** Tickets feature (F1–F5, F7): project ticket board, detail/edit, carnet,
+ *  links & assignments, and clickable `#ref` navigation. */
+
+export { TicketsView } from "./TicketsView";
+export type { TicketsViewProps } from "./TicketsView";
+export { TicketsPanel } from "./TicketsPanel";
+export type { TicketsPanelProps } from "./TicketsPanel";
+export { TicketDetail } from "./TicketDetail";
+export type { TicketDetailProps } from "./TicketDetail";
+export { useTickets } from "./useTickets";
+export type { TicketsViewModel } from "./useTickets";
+export { useTicketDetail } from "./useTicketDetail";
+export type { TicketDetailViewModel } from "./useTicketDetail";
+export {
+  TicketRef,
+  StatusBadge,
+  PriorityBadge,
+  linkifyTicketRefs,
+  statusLabel,
+  priorityLabel,
+  linkKindLabel,
+} from "./ticketMeta";