test(xl-pdf-exporter): bump testTimeout to 15s to avoid CI flakiness

The first "should export a document" test cold-starts PDFExporter and
occasionally exceeds the default 5s timeout in CI (observed at 5029ms),
while subsequent tests in the same file run in <400ms.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: nperez0111

packages/xl-pdf-exporter/vite.config.ts

@@ -9,6 +9,7 @@ export default defineConfig((conf) => ({
   test: {
     environment: "jsdom",
     setupFiles: ["./vitestSetup.ts"],
+    testTimeout: 15000,
     // assetsInclude: [
     //   "**/*.woff",
     //   "**/*.woff2",