feat(tickets): affiche le créateur d'un ticket et filtre la liste par créateur

createdBy était déjà présent dans le frontmatter des tickets mais ni exposé
ni exploitable côté UI. Ajout du DTO (domain/ports/mock), affichage dans
TicketDetail, colonne/filtre créateur dans TicketsPanel, et persistance du
filtre. ticketActor.ts introduit pour porter la logique de filtrage côté
frontend, sans changement backend nécessaire (lot frontend pur).

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

frontend/src/features/tickets/tickets.test.tsx

@@ -103,6 +103,28 @@ describe("MockTicketGateway", () => {
     expect(search.items.map((i) => i.ref)).toEqual(["#2"]);
   });
 
+  it("filters by creator and exposes createdBy on summaries (#109)", async () => {
+    await ticket.create(PROJECT_ID, { title: "User ticket" });
+    const agentTicket = await ticket.create(PROJECT_ID, { title: "Agent ticket" });
+    ticket._seedTicket(PROJECT_ID, {
+      ...agentTicket,
+      createdBy: { kind: "agent", agentId: "agent-1" },
+    });
+
+    const byUser = await ticket.list(PROJECT_ID, { createdBy: { kind: "user" } });
+    expect(byUser.items.map((i) => i.title)).toEqual(["User ticket"]);
+    expect(byUser.items[0]?.createdBy).toEqual({ kind: "user" });
+
+    const byAgent = await ticket.list(PROJECT_ID, {
+      createdBy: { kind: "agent", agentId: "agent-1" },
+    });
+    expect(byAgent.items.map((i) => i.title)).toEqual(["Agent ticket"]);
+    expect(byAgent.items[0]?.createdBy).toEqual({
+      kind: "agent",
+      agentId: "agent-1",
+    });
+  });
+
   it("combines status and priority facets with AND (#12)", async () => {
     await ticket.create(PROJECT_ID, {
       title: "a",
@@ -419,6 +441,45 @@ describe("TicketsView", () => {
     );
   });
 
+  it("shows ticket creators and filters the list by creator (#109)", async () => {
+    const creator = await seedAgent(agent, "CreatorAgent");
+    await ticket.create(PROJECT_ID, { title: "Created by user" });
+    const agentTicket = await ticket.create(PROJECT_ID, {
+      title: "Created by agent",
+    });
+    ticket._seedTicket(PROJECT_ID, {
+      ...agentTicket,
+      createdBy: { kind: "agent", agentId: creator.id },
+    });
+    const listSpy = vi.spyOn(ticket, "list");
+
+    renderView(ticket, system, agent);
+
+    await screen.findByText("Created by user");
+    expect(screen.getByText("Créé par : Utilisateur")).toBeTruthy();
+    expect(screen.getByText("Créé par : Agent : CreatorAgent")).toBeTruthy();
+
+    fireEvent.click(screen.getByLabelText("filter by creator"));
+    fireEvent.click(await screen.findByRole("option", { name: "CreatorAgent" }));
+
+    await waitFor(() =>
+      expect(listSpy.mock.calls.at(-1)?.[1]?.createdBy).toEqual({
+        kind: "agent",
+        agentId: creator.id,
+      }),
+    );
+    await waitFor(() => expect(screen.queryByText("Created by user")).toBeNull());
+    expect(screen.getByText("Created by agent")).toBeTruthy();
+
+    fireEvent.click(screen.getByText("Created by agent"));
+    const dialog = await screen.findByRole("dialog", {
+      name: `ticket ${agentTicket.ref}`,
+    });
+    expect(
+      within(dialog).getByText("Créé par : Agent : CreatorAgent"),
+    ).toBeTruthy();
+  });
+
   it("opens the detail and edits status with a version bump", async () => {
     const t = await ticket.create(PROJECT_ID, { title: "Editable" });
     renderView(ticket, system, agent);