Web: redesign, logo, PWA, QR codes, Spotify guidance

- Album-art-tinted cards that crossfade on song change, equalizer bars,
  live avatar rings, drifting ambient colour, Space Grotesk display font,
  brand purple-to-blue gradient from the logo
- Feed cards rise in and glide to new positions (motion); respects
  reduced-motion
- New logo as nav mark, favicon and Apple touch icon
- Installable PWA: manifest, maskable icons, small service worker
  (cached build assets + offline page), security headers
- Show-QR-code on your own profile; centred profile header with stats
- Settings explains connecting Spotify via Last.fm or ListenBrainz

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MzFywujuH9TiuXbr9vjoX8

apps/web/Dockerfile

@@ -31,6 +31,7 @@ ENV NODE_ENV=production \
     HOSTNAME=0.0.0.0
 COPY --from=builder --chown=node:node /app/apps/web/.next/standalone ./
 COPY --from=builder --chown=node:node /app/apps/web/.next/static ./apps/web/.next/static
+COPY --from=builder --chown=node:node /app/apps/web/public ./apps/web/public
 USER node
 EXPOSE 3737
 HEALTHCHECK --interval=10s --timeout=3s --start-period=10s --retries=3 \