feat(tickets): ajoute les pièces jointes sur tickets (#108)

Stockage flat côté ticket + métadonnées d'attachments, lecture exposée côté
backend/MCP, et UI minimale de liste/ajout dans TicketDetail. Traverse le
domaine (Issue, ports), l'application (usecases + assistant de ticket), les
adaptateurs infra/MCP (issues store, orchestrateur), les DTO backend/web-
server/app-tauri, et le frontend (domain/ports/adapters/hooks/UI).

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

frontend/src/adapters/ticket.test.ts

@@ -54,4 +54,47 @@ describe("TauriTicketGateway invoke payloads", () => {
       },
     });
   });
+
+  it("wraps ticket attachment commands in the request DTO", async () => {
+    const gateway = new TauriTicketGateway();
+
+    await gateway.addAttachment(
+      "proj-1",
+      "#12",
+      "/tmp/note.txt",
+      3,
+      "text/plain",
+    );
+    await gateway.readAttachment("proj-1", "#12", "att-1");
+    await gateway.markAttachmentSummarized("proj-1", "#12", "att-1", 4);
+
+    expect(invoke).toHaveBeenNthCalledWith(1, "ticket_attachment_add", {
+      request: {
+        projectId: "proj-1",
+        ref: "#12",
+        path: "/tmp/note.txt",
+        expectedVersion: 3,
+        mime: "text/plain",
+      },
+    });
+    expect(invoke).toHaveBeenNthCalledWith(2, "ticket_attachment_read", {
+      request: {
+        projectId: "proj-1",
+        ref: "#12",
+        attachmentId: "att-1",
+      },
+    });
+    expect(invoke).toHaveBeenNthCalledWith(
+      3,
+      "ticket_attachment_mark_summarized",
+      {
+        request: {
+          projectId: "proj-1",
+          ref: "#12",
+          attachmentId: "att-1",
+          expectedVersion: 4,
+        },
+      },
+    );
+  });
 });