Add simple traffic analytics with source attribution and conversion funnel

- track.js captures first-touch source per session (utm_source/src param
  or external referrer domain) and logs bridge/start page views.
- Join clicks now carry the source; all events aggregate per-source in
  data/analytics.json on the persistent volume.
- Admin: new Traffic & Conversions card with funnel totals (bridge ->
  start -> join click rates) and a per-source breakdown table.

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

public/admin.js

@@ -5,9 +5,24 @@ function showToast(msg){toast.textContent=msg;toast.classList.add('show');setTim
 async function api(url,opts={}){const r=await fetch(url,{headers:{'Content-Type':'application/json',...(opts.headers||{})},...opts});const d=await r.json().catch(()=>({}));if(!r.ok)throw new Error(d.error||'Request failed');return d}
 async function loadState(){try{state=await api('/api/admin/state');loginView.classList.add('hidden');adminView.classList.remove('hidden');render()}catch(e){loginView.classList.remove('hidden');adminView.classList.add('hidden')}}
 function statusClass(s){return `status status-${s}`}
+function pct(n,d){return d?`${Math.round((n/d)*100)}%`:'—'}
+function renderAnalytics(){
+  const src=(state.analytics&&state.analytics.sources)||{};
+  const tot={bridge:0,start:0,click:0};
+  const list=Object.entries(src).map(([name,r])=>{tot.bridge+=r.bridge||0;tot.start+=r.start||0;tot.click+=r.click||0;return{name,bridge:r.bridge||0,start:r.start||0,click:r.click||0}})
+    .sort((a,b)=>b.click-a.click||b.start-a.start||b.bridge-a.bridge);
+  document.getElementById('funnelStats').innerHTML=
+    `<div class="fact"><small>Bridge views</small><strong>${tot.bridge}</strong></div>`+
+    `<div class="fact"><small>Start views</small><strong>${tot.start}</strong></div>`+
+    `<div class="fact"><small>Join clicks</small><strong>${tot.click}</strong></div>`+
+    `<div class="fact"><small>Bridge → Start</small><strong>${pct(tot.start,tot.bridge)}</strong></div>`+
+    `<div class="fact"><small>Start → Join</small><strong>${pct(tot.click,tot.start)}</strong></div>`;
+  document.getElementById('trafficRows').innerHTML=list.map(r=>`<tr><td><strong>${esc(r.name)}</strong></td><td>${r.bridge}</td><td>${r.start}</td><td>${r.click}</td><td>${pct(r.click,r.start)}</td></tr>`).join('')||'<tr><td colspan="5" class="empty">No traffic recorded yet.</td></tr>';
+}
 function esc(s){return String(s??'').replace(/[&<>'"]/g,c=>({'&':'&amp;','<':'&lt;','>':'&gt;',"'":'&#39;','"':'&quot;'}[c]))}
 function render(){
   const sponsors=[...state.sponsors].sort((a,b)=>a.sortOrder-b.sortOrder);rows.innerHTML=sponsors.map((s,i)=>`<tr><td>${i+1}</td><td><strong>${esc(s.name)}</strong><div class="micro" style="margin:2px 0 0">ID ${esc(s.id)}</div></td><td>${esc(s.parentId||'—')}</td><td><strong>${s.directs}/2</strong></td><td>${levelSelect(s)}</td><td><span class="${statusClass(s.status)}">${esc(s.status)}</span></td><td>${s.clicks||0}</td><td><div class="actions">${s.status!=='qualified'?`<button class="btn btn-secondary btn-sm" data-action="inc" data-id="${esc(s.id)}">+1 Direct</button><button class="btn btn-teal btn-sm" data-action="qualify" data-id="${esc(s.id)}">Qualified</button>`:`<button class="btn btn-secondary btn-sm" data-action="reset" data-id="${esc(s.id)}">Reset</button>`}${s.status==='waiting'?`<button class="btn btn-secondary btn-sm" data-action="activate" data-id="${esc(s.id)}">Make Active</button>`:''}<button class="btn btn-secondary btn-sm" data-action="up" data-id="${esc(s.id)}">↑</button><button class="btn btn-secondary btn-sm" data-action="down" data-id="${esc(s.id)}">↓</button><button class="btn btn-danger btn-sm" data-action="delete" data-id="${esc(s.id)}">×</button></div></td></tr>`).join('')||'<tr><td colspan="8" class="empty">No sponsors in the queue.</td></tr>';
+  renderAnalytics();
   const f=document.getElementById('configForm'),c=state.config;for(const k of ['siteName','programName','bridgeHeadline','bridgeSubheadline','premiumEntryPol','dappReferralBaseUrl','telegramUrl','supportLabel'])if(f.elements[k])f.elements[k].value=c[k]??'';f.elements.showSponsorName.checked=!!c.showSponsorName;f.elements.showQueueProgress.checked=!!c.showQueueProgress;
 }
 document.getElementById('loginForm').addEventListener('submit',async e=>{e.preventDefault();const err=document.getElementById('loginError');err.textContent='';try{await api('/api/admin/login',{method:'POST',body:JSON.stringify({password:document.getElementById('password').value})});document.getElementById('password').value='';await loadState()}catch(x){err.textContent=x.message}});