fix: use local demo data when apiKey is 'demo', avoid CORS issues on HF

index.html

@@ -775,7 +775,7 @@ function computeBB(closes, period = 20, mult = 2) {
 
 // ── API ──────────────────────────────────────────────────────────────────────
 async function fetchSeries(symbol, interval, n, apiKey) {
-  if (!apiKey) return { data: generateDemo(symbol, interval, n), demo: true };
+  if (!apiKey || apiKey === 'demo') return { data: generateDemo(symbol, interval, n), demo: true };
   try {
     const r = await fetch(`${BASE}/time_series?symbol=${encodeURIComponent(symbol)}&interval=${interval}&outputsize=${n}&apikey=${apiKey}`);
     const json = await r.json();
@@ -797,7 +797,7 @@ async function fetchQuote(symbol, apiKey) {
     'BTC/USD': { name:'Bitcoin / US Dollar',   close:'65420.00', change:'-320.50', percent_change:'-0.49%', volume:'—',         open:'65740.00', high:'66100.00', low:'64800.00' },
     'EUR/USD': { name:'Euro / US Dollar',      close:'1.0852', change:'+0.0021', percent_change:'+0.19%', volume:'—',         open:'1.0831', high:'1.0870', low:'1.0820' },
   };
-  if (!apiKey) return { q: DEMO_QUOTES[symbol] || {}, demo: true };
+  if (!apiKey || apiKey === 'demo') return { q: DEMO_QUOTES[symbol] || {}, demo: true };
   try {
     const r = await fetch(`${BASE}/quote?symbol=${encodeURIComponent(symbol)}&apikey=${apiKey}`);
     const json = await r.json();