Profile build-out (avatar + bio) + shareable bio page with QR

- Profile pane: avatar upload + bio, with a link to your public page
- Wall becomes a bio page: avatar, bio, scannable join QR, line ladder, join CTA
- qrcode npm dep; /api/qr renders SVG QR server-side (CSP-clean img)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

public/assets/wall.js

@@ -12,7 +12,12 @@
     IAP.$('wallJoin').href = '/my';
     return;
   }
-  title.innerHTML = 'The <em>' + String(w.name).replace(/[&<>]/g, '') + '</em> line';
+  const safeName = String(w.name).replace(/[&<>]/g, '');
+  title.innerHTML = safeName;
+  IAP.$('bioHead').hidden = false;
+  if (w.avatarUrl) { const av = IAP.$('bioAvatar'); av.src = w.avatarUrl; av.hidden = false; }
+  IAP.$('bioText').textContent = w.bio || 'Building a team on InstantAdPay — join through this page and you\'re in my line.';
+  if (w.qrUrl) IAP.$('bioQr').src = w.qrUrl;
   IAP.$('wallCtaHead').textContent = 'Join ' + w.name + '’s line';
   IAP.$('wallJoin').href = w.joinUrl;
   const grid = IAP.$('wallGrid');