Force GhostScript orientation

GhostScript is incorrectly inferring the orientation of a slide by looking at the rotation of SVG elements such as whiteboard text. This PR forces GhostScript to retain the orientation of each page.

bbb-export-annotations/workers/process.js

@@ -423,6 +423,7 @@ async function processPresentationAnnotations() {
   const serverFilenameWithExtension = `${sanitizedServerFilename}.pdf`;
   const mergePDFs = [
     '-dNOPAUSE',
+    '-dAutoRotatePages=/None',
     '-sDEVICE=pdfwrite',
     `-sOUTPUTFILE="${path.join(outputDir, serverFilenameWithExtension)}"`,
     `-dBATCH`].concat(ghostScriptInput);