Mini App join funnel: startapp sponsor attribution + wallet-app handoff

- /app decodes startapp=<sponsorId>[_<angle>] -> unlinked visitors land on the
  sponsor squeeze page /join/<ref>?src=miniapp (linked members still go to
  their dashboard); no-invite prospects get a gold Join button -> /join-now
- tg-app.js: sync __rmcInTg flag; external links route out of the webview via
  openLink/openTelegramLink (wallet deep links reach the wallet app reliably)
- join-now.js in the webview leads with the MetaMask/Trust deep links (no
  injected wallet can exist there); ref + src survive into the wallet browser
- tgbot: links command + weekly digest include the t.me/<bot>/<short>?startapp
  Telegram-native invite once config.miniAppShortName is set (new PATCH key)
- Synced chat.js canned answer + AI prompt (prospects can join from the app)

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

public/join-now.js

@@ -191,6 +191,15 @@ fetch('/api/public/config').then(function(r){return r.json()}).then(function(c){
   }
   document.addEventListener('DOMContentLoaded',function(){
     loadSponsor();
+    // Telegram Mini App webview: no wallet can ever be injected here, so lead
+    // with the deep links immediately — the join finishes in the wallet app's
+    // own browser (same page, sponsor + attribution carried in the URL).
+    if(window.__rmcInTg){
+      showWalletHelp();
+      var hd=$('walletHelp')&&$('walletHelp').firstElementChild;
+      if(hd)hd.textContent='📱 One tap to finish in your wallet app.';
+      log('You’re in Telegram — joining happens in your wallet app’s secure browser. Tap your wallet above; this page reopens there with your sponsor already set.','ok');
+    }
     $('connectBtn').addEventListener('click',connect);
     $('joinBtn').addEventListener('click',doJoin);
     var fb=$('fundBtn'); if(fb)fb.addEventListener('click',openMoonpay);