pdfDoc was a plain variable (not \$state), so renderer.isLoaded had no
reactive dependencies in Svelte 5. PdfControls received isLoaded=false
permanently, keeping the next-page button disabled while zoom buttons
(which have no disabled attribute) still worked.
Fix: derive isLoaded from totalPages (\$state) via totalPages > 0.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>