Add a QR code sharing option alongside existing copy buttons. When clicked, opens a popover with: - QR code encoding the room's share URL - "Scan to Join" heading - Clickable copy button for the URL Uses qrcode.react library with Radix UI popover component. Button styled with orange gradient to differentiate from existing blue link and purple code copy buttons. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>