Free members refer from day one: share codes with late chain binding

Every account gets a share code at signup; /join/<code> attributes
first-touch site-side and resolves to the referrer's CURRENT on-chain id at
the referral's buy time, so activating any time before your people buy
locks the line to you. Joining through a code emails the referrer an
activate-payouts nudge. Buy flow re-resolves the sponsor at click time.
Copy updated across home and members; assets bumped to v=20260904g.

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

public/assets/home.js

@@ -5,10 +5,11 @@
   IAP.$('contractLink').href = c.explorer + '/address/' + c.contract;
 
   const sp = await (await fetch('/api/sponsor')).json();
-  if (sp.sponsorId) {
+  if (sp.invited) {
     const el = IAP.$('sponsorLine');
     el.hidden = false;
-    el.textContent = 'You were invited by member #' + sp.sponsorId + '. Your purchases pay their team, and your own link will do the same for you.';
+    el.textContent = (sp.sponsorId ? 'You were invited by member #' + sp.sponsorId + '.' : 'You arrived through a member’s invite.')
+      + ' Your purchases pay their team, and your own link will do the same for you.';
   }
 
   async function loadLadder() {
@@ -41,7 +42,10 @@
         await IAPWallet.signIn();
       }
       IAP.status('Confirm the purchase in your wallet…');
-      const r = await IAPWallet.buy(Number(btn.dataset.id), sp.sponsorId || 0, btn.dataset.cost);
+      // resolve the sponsor at buy time: a code referrer who activated since
+      // page load still gets locked in
+      const spNow = await (await fetch('/api/sponsor')).json();
+      const r = await IAPWallet.buy(Number(btn.dataset.id), spNow.sponsorId || 0, btn.dataset.cost);
       if (r.receipt.status !== '0x1') throw new Error('Transaction reverted. Check the explorer.');
       IAP.status('Purchase settled on-chain. Credits are yours, payouts delivered. Watch it on the ledger.', 'ok');
       IAP.refreshNavWallet();