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/projects/ProjectsView.tsx

@@ -39,6 +39,7 @@ import { MemoryPanel } from "@/features/memory";
 import { EmbedderSettings } from "@/features/embedder";
 import { PermissionsPanel } from "@/features/permissions";
 import { ProjectWorkStatePanel } from "@/features/workstate";
+import { TicketsView } from "@/features/tickets";
 import { ConversationViewer } from "@/features/conversations";
 import { GitPanel, GitGraphView } from "@/features/git";
 import { Button, Input, Panel, Tabs, cn } from "@/shared";
@@ -50,6 +51,7 @@ type SidebarTab =
   | "projects"
   | "context"
   | "work"
+  | "tickets"
   | "agents"
   | "templates"
   | "skills"
@@ -61,6 +63,7 @@ const SIDEBAR_TABS: { id: SidebarTab; label: string }[] = [
   { id: "projects", label: "Projects" },
   { id: "context", label: "Context" },
   { id: "work", label: "Work" },
+  { id: "tickets", label: "Tickets" },
   { id: "agents", label: "Agents" },
   { id: "templates", label: "Templates" },
   { id: "skills", label: "Skills" },
@@ -304,6 +307,14 @@ export function ProjectsView() {
               <p className="text-sm text-muted">Open a project to view work state.</p>
             )}
 
+            {/* Tickets panel */}
+            {sidebarTab === "tickets" && active && (
+              <TicketsView projectId={active.id} />
+            )}
+            {sidebarTab === "tickets" && !active && (
+              <p className="text-sm text-muted">Open a project to view tickets.</p>
+            )}
+
             {/* Agents panel — only rendered when active project exists */}
             {sidebarTab === "agents" && active && (
               <AgentsPanel projectId={active.id} projectRoot={active.root} />