Wall ownership ladder: positions 2 and 3 become the member's own at 2 / 5 qualifying buyers

- accounts.wall_offers (JSON, up to 2 offers: label, https link, banner) set from
  Profile > Your wall; upload supported; locks show the buyer threshold.
- /api/wall assembles: position 1 = own line banner; positions 2-3 = own offer
  when unlocked and set, else upline banners (only uplines with a live banner),
  else house ads. Response carries unlocked + buyerCount; wall labels show
  "this wall" / "their line" / "InstantAdPay".
- Chatbot canned answer + facts, follow-up email 7 mention the ladder.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

public/assets/wall.js

@@ -64,7 +64,7 @@
     const creative = m.bannerUrl
       ? '<img src="' + m.bannerUrl + '" alt="' + safe + ' banner">'
       : '<b>' + safe + '</b><br><span class="muted small">' + (m.targetUrl ? 'visit their site' : 'banner slot open') + '</span>';
-    d.innerHTML = '<div class="wall-pos">Position ' + (i + 1) + (i === 0 ? ' · this wall' : '') + '</div>'
+    d.innerHTML = '<div class="wall-pos">Position ' + (i + 1) + (m.own ? ' · this wall' : m.admin ? ' · InstantAdPay' : ' · their line') + '</div>'
       + '<div class="wc-creative">' + creative + '</div>'
       + '<div class="wc-action"></div>'
       + '<div class="small muted" style="margin-top:8px">' + safe + '</div>';