Add diagnostic logging to fig export roundtrip test

Test has never passed since it was added (3b32b4d). Add console.log
to show page counts, node counts, and internal-only flags so the CI
log reveals what the export→parse roundtrip actually produces.

tests/engine/fig-export-worker.test.ts

@@ -82,9 +82,26 @@ heavy('fig export roundtrip', () => {
   })
 
   test('exported file can be parsed back', async () => {
+    const originalPages = parsed.getPages()
+    const originalNodes = [...parsed.getAllNodes()].length
+    console.log(`Original: ${originalPages.length} pages, ${originalNodes} nodes`)
+    for (const p of originalPages) {
+      console.log(`  page "${p.name}" children=${parsed.getChildren(p.id).length}`)
+    }
+
     const exported = await exportFigFile(parsed)
+    console.log(`Exported: ${exported.length} bytes`)
+
     const reparsed = await parseFigFile(exported.buffer as ArrayBuffer)
+    const reparsedPages = reparsed.getPages()
+    const reparsedAllPages = reparsed.getPages(true)
+    const reparsedNodes = [...reparsed.getAllNodes()].length
+    console.log(`Reparsed: ${reparsedPages.length} pages (${reparsedAllPages.length} incl internal), ${reparsedNodes} nodes`)
+    for (const p of reparsedAllPages) {
+      console.log(`  page "${p.name}" internal=${p.internalOnly} children=${reparsed.getChildren(p.id).length}`)
+    }
+
     expect(reparsed).toBeInstanceOf(SceneGraph)
-    expect(reparsed.getPages().length).toBeGreaterThan(0)
+    expect(reparsedPages.length).toBeGreaterThan(0)
   })
 })