- Add /qr endpoint serving SVG (uses existing qrcode crate, svg feature) - Header popover: QR on desktop, direct download link on mobile viewports - Only visible when [mobile] enabled = true in config - Expose mobile.enabled and mobile.port in /stats response - Lazy-load QR on first click, dismiss on outside click Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>