feat(parvagues): add /parvagues/fiche technical rider page

Sleek single-page fiche technique to share with festivals and venues:
show info, artist apport, audio/video/electrical/stage requirements,
SVG stage plot, timings, contact. Print-optimised CSS for dense A4 PDF
export via the browser's print dialog.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>