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/site.css

@@ -349,6 +349,12 @@ textarea{resize:vertical;font:inherit}
 /* ── welcome tour (gauntlet): framed line sites + countdown ── */
 .lgate-frame{flex:1;border:0;width:100%;background:#fff;min-height:0}
 .ggmeta{padding:8px 16px;background:var(--panel-solid);border-bottom:1px solid var(--line)}
+/* ── bio header (wall/profile page) ── */
+.bio-head{display:flex;gap:22px;align-items:center;flex-wrap:wrap;padding:8px 0 4px}
+.bio-avatar{width:96px;height:96px;border-radius:50%;object-fit:cover;border:2px solid var(--mint);flex:0 0 auto}
+.bio-meta{flex:1;min-width:220px}
+.bio-qr{flex:0 0 auto;background:var(--panel);border:1px solid var(--line-strong);border-radius:14px;padding:10px}
+.bio-qr img{display:block;border-radius:8px;background:#eef7f3}
 /* ── wall page ── */
 .wall-card{background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);padding:16px;text-align:center}
 .wall-card img{max-width:100%;border-radius:10px;border:1px solid var(--line-strong)}