fix frontend SVG results and downloads

frontend/tests/a2a.test.mjs

@@ -0,0 +1,21 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import { unwrapSkillResponse } from "../src/a2a.js";
+
+test("unwraps the production invoke response envelope", () => {
+  const result = {
+    status: "ok",
+    svg_assets: [{ name: "sprite.svg", svg: "<svg></svg>" }],
+  };
+
+  assert.deepEqual(
+    unwrapSkillResponse({ result, events: [], artifacts: [], grant_id: null }),
+    result,
+  );
+});
+
+test("keeps direct skill responses compatible", () => {
+  const result = { status: "ok", receipts: [] };
+  assert.equal(unwrapSkillResponse(result), result);
+});