fix: PC layout regression and silent PDF download failure

layout-context: getInitialLayout() was returning verticalSplit for
any stored 'vertical' preference, including on desktop. Now checks
isMobile first so stored mobile preference doesn't bleed into PC.

compile-and-download-pdf: when compile succeeds but output.pdf is
absent from outputFiles, the code crashed silently at outputFile.build
leaving the user with no feedback. Now shows the error modal instead.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

services/web/frontend/js/features/project-list/components/table/cells/action-buttons/compile-and-download-project-pdf-button.tsx

@@ -98,6 +98,10 @@ function CompileAndDownloadProjectPDFButton({
           const outputFile = data.outputFiles
             .filter((file: { path: string }) => file.path === 'output.pdf')
             .pop()
+          if (!outputFile) {
+            setShowErrorModal(true)
+            return
+          }
 
           const params = new URLSearchParams({
             compileGroup: data.compileGroup,

services/web/frontend/js/shared/context/layout-context.tsx

@@ -89,11 +89,11 @@ const MOBILE_MQ = '(max-width: 767px)'
 
 function getInitialLayout(): IdeLayout {
   const stored = localStorage.getItem('pdf.layout')
-  if (stored === 'vertical') return 'verticalSplit'
+  const isMobile = window.matchMedia(MOBILE_MQ).matches
   if (stored === 'flat') return 'flat'
   if (stored === 'split') return 'sideBySide'
-  // No stored preference — default to vertical split on mobile
-  return window.matchMedia(MOBILE_MQ).matches ? 'verticalSplit' : 'sideBySide'
+  if (stored === 'vertical') return isMobile ? 'verticalSplit' : 'sideBySide'
+  return isMobile ? 'verticalSplit' : 'sideBySide'
 }
 
 const reviewPanelStorageKey = `ui.reviewPanelOpen.${getMeta('ol-project_id')}`