Fix candle chart staleness and show live price on today's candle

- Refresh candles on every /candles request instead of only at startup
- Patch today's candle close/high/low with the live BTC price intraday
- Synthesise today's candle from live price if CoinGecko hasn't published it yet
- Display current BTC price next to the chart title

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

btc-portfolio/frontend/src/components/BTCCandlestickChart.js

@@ -39,7 +39,7 @@ const btnStyle = {
   marginLeft: '0.5rem',
 };
 
-export default function BTCCandlestickChart({ candles, purchases, stats, fullscreen, onToggleFullscreen }) {
+export default function BTCCandlestickChart({ candles, purchases, stats, fullscreen, onToggleFullscreen, livePrice }) {
   const containerRef = useRef(null);
   const chartRef = useRef(null);
   const candleSeriesRef = useRef(null);
@@ -167,7 +167,14 @@ export default function BTCCandlestickChart({ candles, purchases, stats, fullscr
   return (
     <div style={fullscreen ? fullscreenStyle : cardStyle}>
       <div style={headerStyle}>
-        <div style={titleStyle}>BTC Candles (EUR)</div>
+        <div style={titleStyle}>
+          BTC Candles (EUR)
+          {livePrice != null && (
+            <span style={{ fontSize: '0.9rem', fontWeight: 400, color: '#ccc', marginLeft: '0.75rem' }}>
+              €{livePrice.toLocaleString()}
+            </span>
+          )}
+        </div>
         <div>
           <button style={btnStyle} onClick={handleSave}>Save as PNG</button>
           <button style={btnStyle} onClick={onToggleFullscreen}>

btc-portfolio/frontend/src/pages/Dashboard.js

@@ -208,6 +208,7 @@ export default function Dashboard() {
           candles={activeCandles?.candles ?? null}
           purchases={activeCandles?.purchases ?? purchases}
           stats={stats}
+          livePrice={stats?.current_price ?? null}
           fullscreen={fullscreenChart}
           onToggleFullscreen={handleToggleFullscreen}
         />