Remove download button on mobile, keep only Open in New Tab

iOS Safari doesn't support programmatic downloads reliably.

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

src/components/shared/file-viewer.tsx

@@ -333,10 +333,9 @@ function FileItem({ file }: { file: ProjectFile }) {
           </div>
         </div>
 
-        {/* Mobile action buttons — no inline preview on mobile, just open + download */}
+        {/* Mobile action button — open in new tab only (download unreliable on iOS) */}
         <div className="flex md:hidden items-center gap-2 mt-3 pt-3 border-t">
           <FileOpenButton file={file} className="flex-1" label="Open in New Tab" />
-          <FileDownloadButton file={file} className="flex-1" label="Download" />
         </div>
       </div>