fix: keep release archive wrapped in a folder

tests/package-release-archive.test.ts

@@ -6,7 +6,7 @@ import { describe, expect, test } from "vitest";
 import { createReleaseArchive } from "../scripts/package-release-archive.mjs";
 
 describe("package-release-archive", () => {
-  test("creates a zip archive without relying on the system zip binary", async () => {
+  test("creates a zip archive with a top-level release folder", async () => {
     const tempDir = await mkdtemp(path.join(os.tmpdir(), "release-archive-"));
     const sourceDir = path.join(tempDir, "source");
     const archivePath = path.join(tempDir, "archive.zip");
@@ -21,5 +21,8 @@ describe("package-release-archive", () => {
 
     const archive = await readFile(archivePath);
     expect(archive.byteLength).toBeGreaterThan(0);
+    expect(archive.toString("utf8")).toContain(
+      "star-chart-search-enhancer-internal/hello.txt"
+    );
   });
 });