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/adapters/index.ts

@@ -27,6 +27,7 @@ import { TauriGitGateway } from "./git";
 import { TauriPermissionGateway } from "./permission";
 import { TauriWorkStateGateway } from "./workState";
 import { TauriConversationGateway } from "./conversation";
+import { TauriTicketGateway } from "./ticket";
 
 function notImplemented(what: string): never {
   const err: GatewayError = {
@@ -61,6 +62,7 @@ export function createTauriGateways(): Gateways {
     permission: new TauriPermissionGateway(),
     workState: new TauriWorkStateGateway(),
     conversation: new TauriConversationGateway(),
+    ticket: new TauriTicketGateway(),
   };
 }
 
@@ -80,4 +82,5 @@ export {
   TauriPermissionGateway,
   TauriWorkStateGateway,
   TauriConversationGateway,
+  TauriTicketGateway,
 };