Make every dollar figure evergreen via the live POL price

The config API now carries the hourly-cached polUsd; the start page,
training callout, join-page shortfall, and chatbot (canned + AI
prompt) all compute entry dollars live instead of quoting stale
numbers. Post 6/7 copy drops hard "$27 = entry" claims for
pocket-change framing (the video's $27 stays - it describes weekly
wasted spending, which is evergreen).

public/start.js

@@ -13,6 +13,10 @@ async function load(){
     document.getElementById('progressBar').style.width=`${Math.min(100,(currentSponsor.directs/2)*100)}%`;
     document.getElementById('entryPol').textContent=c.premiumEntryPol;
     document.getElementById('entryPol2').textContent=c.premiumEntryPol;
+    if(c.polUsd>0){
+      var usd=Math.round(c.premiumEntryPol*c.polUsd);
+      ['entryUsd','entryUsd2'].forEach(function(id){var el=document.getElementById(id);if(el)el.textContent=' (~$'+usd+' today — POL’s price moves)';});
+    }
     document.getElementById('joinButton').href='/join-now';
     {const dl=document.getElementById('dappJoinLink');if(dl&&currentSponsor.referralUrl){dl.href=currentSponsor.referralUrl;dl.classList.remove('hidden');}}
     document.getElementById('queueText').textContent=c.showQueueProgress?`${s.waitingCount} team placement${s.waitingCount===1?'':'s'} waiting behind the current sponsor.`:'';