refactor(tests): centralize test harness boilerplate into bundle.mjs helper

tests/run-fullbook-test.mjs

@@ -2,12 +2,10 @@
 // renderer assembly + Tiptap modules, and verifies that a book assembled from
 // native chapters renders with correct chapter order, page-break anchors,
 // reorder behavior, title injection, and Copy-All native fidelity.
-import esbuild from "esbuild";
 import fs from "fs";
-import os from "os";
 import path from "path";
-import url from "url";
 import { JSDOM } from "jsdom";
+import { bundleForTest } from "./helpers/bundle.mjs";
 
 const dom = new JSDOM("<!DOCTYPE html><html><body></body></html>", {
   pretendToBeVisual: true,
@@ -26,19 +24,10 @@ g.DOMParser = window.DOMParser;
 g.requestAnimationFrame = (cb) => setTimeout(cb, 0);
 g.cancelAnimationFrame = (id) => clearTimeout(id);
 
-const out = path.join(os.tmpdir(), `folio-fullbook-${process.pid}.mjs`);
-const entry = path.resolve("tests/.folio-fullbook-test-entry.ts");
-await esbuild.build({
-  entryPoints: [entry],
-  bundle: true,
-  platform: "node",
-  format: "esm",
-  outfile: out,
-  write: true,
-  logLevel: "silent",
+const { mod, cleanupBundle } = await bundleForTest({
+  name: "folio-fullbook",
+  entryPoints: ["tests/.folio-fullbook-test-entry.ts"],
 });
-
-const mod = await import(url.pathToFileURL(out).href);
 const {
   buildFullBookDoc,
   nativeNodeText,
@@ -190,6 +179,6 @@ ok(
   "empty book assembles to empty doc"
 );
 
-fs.rmSync(out, { force: true });
+cleanupBundle();
 console.log("\nFull Book tests: " + (failures === 0 ? "ALL PASSED" : failures + " FAILED"));
 process.exit(failures === 0 ? 0 : 1);