Facebook Group PDF Viewer Integration

I want members of my Facebook group to open and read PDF attachments right inside the desktop interface instead of downloading them first. The core must be a lightweight, on-page PDF viewer that activates when someone clicks the file in a post.

Essential capability
• Search within PDF (find text string, highlight next/previous matches).

Nice-to-have (mention if your approach already covers them)
• Zoom controls
• Page navigation buttons

I’m open to solutions ranging from an embedded HTML5 viewer loaded through a shareable link to a small browser extension or any other method that stays within Facebook’s terms of service. All code should be clean and easy for me to update with future PDF links. A quick setup guide and a brief note on any third-party libraries you use will complete the delivery.