- Rename route from :id/qr-code to :id/qr per TEC-3071 spec
- Add ?size=N (50-1000, default 300) query param for PNG width control
- Add ?format=png|svg query param; SVG path uses QRCode.toString with type:svg
- Set correct Content-Type (image/png or image/svg+xml) and Cache-Control headers
- Add 4 unit tests covering PNG/SVG dispatch, cache header, and 404 path
- OG meta tags on listing detail SSR already complete (no changes needed)
Co-Authored-By: Paperclip <noreply@paperclip.ing>